To state the obvious you cannot have it both ways. If you like the roominess the slides provide when you are parked they have to go somewhere when you are towing. :(
Since my DW and I stop at placed on the way for potty breaks and snacks, we made sure the TT was useable with the slide in. This means that our slide is only about 14 or 16 inches deep. However it is 14 feet long with the kitchen and couch, so half of our 25 foot wall moves out when we are parked. :)
The worst combination I saw, was a large living room slide that stopped up against the bathroom door when retracted. That would never do for us old folks.:S