Hi Neil,
I did the change over last year while I was parked in Happy Trails AZ, it's not that big a deal.
I replaced the Sony with a HD/Wifi Samsung 42" that I picked up at Costco. To remove the old Sony does take some Horse Power(a 2 man job). If you pull the screws from the covered panel you can the see the back of the Sony TV set the Samsung did bolt right into the original frame( the hole patterns are standard we have an 06 coach).
I also pull the old Sony sound system and DVD/VHS player. I replace both with a Sony home theater system. The new system does come with some very nice speakers but I decided to change all the speakers but I did change the woofer to the new Sony Woofer it was smaller and looked like a better unit then the old unit .
The new TV has 3 times the picture of the old system and the home theater is great. We now have one remote and enjoy the features offered with wifi direct including Netflix.
I did clean up the wiring what a birds nest!! I also pull all of the Satellite cables as I just don't use this feature but should you want the Sat service it's not a problem.