RV garage

I have a large garage. I attached to house with a breezeway to simplify insurance.

No moisture or rust problems in Reno. I would have a place to dump tanks.

If I didn't have a concern about security, I would extend the garage roof for a carport for my rig - and put in on a slab. A roof for shade and out of nature's elements would be my main goal.

A 14ft high door

Power for a welder (size depends on welder).
MORE STORAGE. Seems like there is never enough.
Alarm on the roll up garage door as well as side door.
Better Ventilation for summer, insulation for winter. A/C and heat seems extravagant until it's really hot or really cold.

Do you mean compressed air supply connections?
I would think about:
Big exhaust fans
More lighting that you think
Wider door than you think (14 feet)
Taller door than you need
Outlets everywhere
In-floor heat (but I am in Minnesota)
Deep enough to leave the truck hooked up and the door closed
Hot water is more useful than you think...if you can swing it.
Inserts in the floor like 2" receivers....many uses.
floor drain the full length
Truck lift
Shower/head/hot tub
Full kitchen
On and on and on...

do not sit it on the bare ground moisture will rust out every thing, under the rv.