Welcome to iRV2 and the vintage Newmar family .
I installed a combo unit , used the marked location from the pre plumb ,and honestly can't say if the wall would allow a higher location for the vent .
I actually had to raise the floor 4" to line up the vent .
It might be worthwhile to put a small hole where marked on the panel and have a look up , the panel can be patched ; after all it'll be hidden.
I've seen dryer vent adaptors , I'll see if I can find a picture .
EDIT: Marketed under ; offset, periscope, and adjustable dryer vent ; available at Home Depot and Amazon among others, in a wide range of sizes. .