HITCH BOX FOR THE AIRSTREAM INTERSTATE, PART 1: SCOPING

My husband and I know that we want to get a hitch box for our Airstream Interstate.  External storage space is particularly important because I want to be able to use dry ice in our Yeti cooler, to keep food frozen on a timescale of weeks (I explained my rationale in detail over a year ago in this Air Forums thread).  I am not comfortable having dry ice sublimating inside the confined space of the Interstate; I'm concerned it could displace oxygen under certain conditions, which could be dangerous.

This pic shows our Yeti Tundra 50 balanced on our rear hitch step, just to show the size of it relative to the Interstate.  This little sucker must remain outside the van so that it doesn't accidentally gas us to death.  

So we need a hitch box to accommodate the Yeti, but as long as we are committing to the purchase of a hitch box, it makes sense to identify the sweet spots in terms of size, price, and functionality - what else might we want to fit into that same box?  Answer:  An inflatable kayak.

I already own a Sea Eagle 330, but it is rather shot at this point due to old age.  So this is not the exact kayak I would take, but for the planning purposes of sizing the hitch box, we used this one because anything larger would be a non-starter for us.  These kayaks have come a long way technologically in recent years, and are worth having, in my opinion.  You can get a lot of boating out of device that rolls up nicely into a small portable package.  

I went through a few iterations as to how I thought the hitch box should be optimally dimensioned, but let me cut to the chase with my final decision:

Nothing gets ordered or created in our house without first being fully mocked up out of cardboard.  That's the Yeti roughly in the center, the Sea Eagle rolled up at right, and the seats, PFDs, and air pump stashed on the left side.  I use the PFDs that have the carbon dioxide inflation cylinders, so they don't take up much space. 

The problem with most of the off-the-shelf hitch boxes I've found on the market is that they are not sufficiently deep for my needs.  I need to be able to lift the lid of the hitch box, reach in, and pop the rubber keepers on the Yeti such that I can open it and retrieve food without having to physically lift it out of the hitch box.  It has to function as a fully open-able box within a box, in other words.  

The magic numbers on this cardboard mock-up, inner dimensions, are 22 inches deep by 40 inches wide by 24 inches tall.  And here's what the mock-up looks like on the back of our Interstate:

It looks about right.  This size doesn't overpower the back of the van.  The one caveat with this configuration is that I don't think any kayak paddles would come close to fitting in a box this size - they're probably all going to be too long, even the click-together kinds that separate into halves.  But paddles are light and linear, plus we always carry a ten-foot Telesteps telescoping ladder, so we are going to be lashing our paddles to the roof rack, beside the solar panels.  If you prefer your paddles down low, you're going to need a bigger box than this.  Or perhaps you could put them in your interior closet.  

Now, having established what would work and how, the challenge becomes sourcing.

To make a long story short, I have done a lot of research and nothing I've seen in the pre-made market has struck me as representing a sensible investment.  One of the most popular hitch box models is called the Stowaway, but I'm not encouraged by the reviews of it, which I've combed over repeatedly.  They are made of plastic, some users complain that they leak rainwater into the interior, and most consequentially, some reviewers claim that fifteen seconds with a crow bar is all it takes to pop one open.  That simply is not sufficient durability or security for the substantial sum of money that the manufacturer is charging for them.

Yeti coolers in particular are ultra-high theft targets - I've read newspaper reports of Yeti theft rings (!!) in the greater Houston area, if you can imagine that.  As the joke goes, the only way to stop a Yeti from being stolen is to buy a Coleman.  While I realize that no hitch box will ever be impenetrable, I want to at least deter the kind of smash-and-grab scenario to which the Stowaway seems too vulnerable.

Our next step is to identify a suitable fabber who might be able to build this for us.  My husband and I don't yet see eye to eye on what the configuration should look like.  Without a doubt, we need some kind of a swing-away mechanism because we use the back doors of the Interstate for ingress-egress.  My mechanical engineer husband is concerned about the moment arm created by having a heavy hitch box on a swing-away hitch platform. The hitch is rated to take the dead weight, but the forces created by lateral swing weren't necessarily what the engineer had in mind when spec'ing that hitch.  So hubster would prefer something that instead attaches directly to the rear bumper for greater strength and stability - but that would probably require us to replace the bumper, and at this point I have yet to be convinced - I'm not really feeling that option ($$$$ ca-CHING!) when a simpler solution might get the job done.  Conversely, if a concrete rationale emerges as to why a non-hitch solution would be strongly preferable, I'm all ears.  The only thing I won't consider at this point is a trailer.  We simply don't need something that large.

Anyway, in one or more near-future posts, I will report on our progress toward finding a fabrication solution.

Updates:  Subsequent links on our solution.

CUSTOM HITCH CARRIER FOR THE AIRSTREAM INTERSTATE, PART 2: OUTSIDE THE BOX

CUSTOM HITCH CARRIER FOR THE AIRSTREAM INTERSTATE, PART 3: TRIM OUT