Key, that's one seriously unique van! Neat!!!!
What brand and size generator? I'm asking because I may have a few ideas.... Roadtrek (Canadian maker of class B van RV's) has used two ways of mounting the Onan 2800 on their Dodge van conversions. In the early '90's, they made some with the genset sitting on the floor in a driver's side compartment. I think the kitchen counter or sink was above it. Later, thru the end of the Dodge Ram van and into their current Chevy production, they've hung them under the rear floor. I've had two like this.
If you happen to see an early-to-mid 90's Roadtrek '190 Independent' Dodge, I'm pretty sure that had the floor-level genset compartment. They also used it in the first series 210, based on the ultra-long version of the Chevy mid-90's G30 van. Pleasureway ('nother B maker) also uses the floor-level mount in their Ford Excels. I think it's under a closet in those.
If yours is an Onan 2800 or something not too much larger, it might be worth sacrificing a little interior space to mount it above the floor like that. Aside from better ground clearance, it'd also be more protected from an accidental dunking, either fording or boat launching.
Good luck with the van. It's plumb awesome!
"Entropy never sleeps. Do y'all?"
'06 Std. cab Tiger CX 4x4, 8.1 & Allison 6 spd, aka 'Loafer's Glory'. Drivin' and smilin'.