tnmrm - my heart goes out to you about this. This situation touches on one of my pet peeves about the way "things" are put together in a way that makes maintenance or repair ridiculously difficult or impossible.
Sailing across the Atlantic on an 80ft sailboat and having to repair something critical mid crossing that had been designed and installed in a difficult reach spot was the topper. Literally some things in a boat require the cutting into the side of the hull to repair.
I see this same "design" flaw baked into RV's, houses, etc. They are designed to look good with no thought as to actual real life use and maintenance/repair down the road. All you DIY types- PLEASE take this into account when building out your rigs.
Your situation - Hopefully REF (maybe PM him) sees this and responds with what he made work for him with his 50 layout (kitchen/fridge cabinet just aft of the driver's seat). It can be done but it is not easy.
When you get into this, certainly consider modifying the current design to make accessibility to the window (and anything else) easier. Windows, water pumps, heaters, batteries, valves, etc. All will need replacing or repair at some point. It will take some thinking out of the "original design" box.
I feel your pain.
Beastie 3: 2002 7.3 EB Cargo: Agile TTB, CCV Mid Top, Custom Walk Through, Lots of stuff added. BlingMyRig.com