Yes! Thank you so much!
LenS, this is exactly the sort of detail I need, so now I'll tackle building boxes with confidence, if not competence. I see that your lids are not hinged, but lift off like a shoe box, right? I hadn't thought of that design, but in fact it will work better with the bikes: just lift up the lid and set it aside, rather than swinging it up on its hinges and whacking the bike wheels. But one more question: how are they locked/secured? Have you put hasps or latches on the boxes?
Silver350 -- "door seal." Yep, either that or the closed cell foam weather-stripping that LenS used should fit the bill. It should be easy to get at Napa or a similar store.
Since I am putting the storage boxes on a HitchHaul, I could secure them using square u-bolts, nuts inside. I’d like to figure out some semi-permanent way to secure them, rather than straps, since I'll be opening at least one box daily (it will have the Coleman stove and fuel in it).
Here, by the way, are photos of the basic setup that I’m working with:
The Hitch Hauler with another receiver piggybacked onto it.
Close up of piggy-backed receiver. Note bolts tapped into top and side to prevent wobble (idea gotten from another thread on this forum!)
My road bike and mountain bike, with clearances to license plate, rear tire, and front fork noted.