I have seen people install a hinge setup to swing the TV up out of the way for travel and then it drops down to watch when stopped.
I would make up a sturdy door to cover the old TV hole and mount hinges on the top. Then mount the TV to the door.
Line the inside of the opening where you took the old TV from and use the area for storage/controls/sat receiver/DVD player/etc.
Locking folding countertop extension brackets will work. Mount them to the door, and then the TV to a piece of 3/4 inch plywood that the TV is mounted to.
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Happy Glamping, Norman & Elna. 2008 Winnebago Adventurer 38J, W24, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with bicycles or KLR 650 in the back.
Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand!