"My understanding is that they're kept at 5 psi when not needed, would they still interfere with what little flex I have?"
I would say yes. On my Ford at 5 psi when empty I mabey have 3-4" to play with. I don't even hit my overload springs. Of course you have a smaller lighter rig so it may react different. Just keep in mind they where designed for load carrying and nothing else. There may be ones designed for allowance of flex but never researched it. Do a quick search on the pirate board, they might have some info on that.