"Screwing the faceplate to the mount sure sounds like a permanent installation, don't you think?"
I don't know where you live, but here in NY we have screw drivers that work in two directions. They both install and remove screws. Maybe you can order one from here if they don't have them in your area.
"What would you suggest I use?"
Look on page 91 of your TM-V71 manual and you will find a part they call the panel bracket that connects to the panel holder. The panel bracket convienently has slotted mounting hole that are open on one end. If you use the fancy bi directional screw driver available in the big city, you could loosen the screw and slip the panel bracket off the Panavise mount.
This way you have a safe and secure mount in the truck, even though it's not used much, and it's easy to remove. The only downside is you will have to order one of those fancy bi directional screwdrivers. Hopefully the hardware stores in your area have screws, nuts, and washers of similar sizes that will work in this application.
Ok, ok. I thought I was the only one allowed to be sarcastic. Geez, at least I gave you one of those winky things.
I think using the panel bracket is a great idea, but I don't think the plastic piece the face plate attaches to is available separately. You have to buy the entire $50 DFK-3D kit. If they were available separately and at a reasonable price, I'd buy two and have one for each vehicle. Until I can find them, I'm looking for another solution...something I am hoping the # 702 Porta Grip will be.