I didn’t say you couldn’t put a strap on it, but then it would just be a cargo container, no? Or a storage board?
The issue isn’t the cost of producing food on the move, any endgame player can afford a few dozen solar panels or a couple of V12s on their truck if it means free, infinite fruits/veg. Ideally, it would be a matter of “You can farm in a static base, can’t farm with a mobile one”. Well, actually ideally static bases would have other advantages making them superior to mobile bases, but for the moment that’s one of the only ones.