Had a similar issue on a prior TT.
My MaxxAir cover 'just' fit but the venting louvers where right in front of the black tank stink pipe......, I always had to remember to keep the bath fan vent closed when not running the fan...., with or without the MaxxAir cover. Running the fan in 'reverse' was a major no-no
2016 GM 2500HD 6.0L/4.10
2018 Jay Flight 24RBS
2002 GM 2500HD 6.0L/4:10 (retired)
2005 Jayco Eagle 278FBS (retired)
1999 Jayco Eagle 246FB (retired)
Reese HP Dual Cam (Strait-Line)