i know it won't necessarily help with your problem of wanting a bedroom wall, but i CAN say i've revamped the floorplan of my Airstream, mainly for the same reason you did. i'm living in it, i want it the way i want it.
my unit is a 1964
26' Overlander, and in '64 they all had rear bath. this one had 2 gauchos. i wanted something a bit more livable. if my mother-in-law visits, i don't want her stumbling over our bed in the middle of the night to reach the can. i don't want to have to 'put away' my bed every day. so we modified our layout based on a 2007 '25 safari rear bed layout. much like your design our bed fills the whole back, and yes, i have to climb over hubby at night. we can deal with it... and sometimes it even leads to a little... ahem...
our mattress is nothing more than 6 inch foam with the back corners cut off to match the curve of the wall, and i use standard full-size sheets on it. because it's foam i can cheat and pull the whole mattress to me as i stand at the hall and stretch the sheet over the corners, then let the mattress spring back into place. no big deal.
our trailer is a bit shorter, so we definately didn't have room to try to go around the wheel wells, you *might* be able to pull it off in a longer trailer, but i don't know. we have the hallway to the back slightly offset to make room for the bathroom. the toilet sits alongside the wheel well, and we squeezed in a tiny black tank for it between the frame cross-members. we bought a tub pan that had a raised lip that sat right over the end of the wheel well and forms a shelf inside the shower. the other wheel well is hidden in the closet/under the kitchen cabinets. our kitchen stayed in the same location. even the fridge is in the same location (saved trying to relocate that vent!
) we routed the tank vents around and out the same holes they originally went out (we even reused the nifty curved pvc pipes we'd pulled out during deconstruction.
we removed 3 windows. one that used to be where the shower wall is now, and two that ended up in storage space. removing them isn't so hard.
for what it's worth, i recently had the opportunity to visit some friends and see the inside of their rigs, wander the kitchen, use the bathroom, etc... and for as small as we are at '26, with our current layout it felt so much more spacious than those other rigs we saw. even our tiny cubby-hole bathroom feels bigger. and i've had more than one person say they've always wanted to see the inside of an Airstream, step inside, and the first thing out of their mouths is "wow, it's so open in here!" or something similar. i guess that's just a reassurance that if you CAN'T quite swing the side-hallway thing, you can still have plenty of space.