Just to give an update. I had "Todd's RV" (recommended by Roadmaster) install the baseplates and light wiring for me in Portland, OR (about $779 total). Nice guy, good work, reasonable price. Then I read all the comments on the internet that the car really needs a charge wire, so I bought the Toad-Charge from RVUpgrades (about $88, shipped). It was easy to install.
I just towed it 1200 miles in 3 days. No trouble at all. I started it each morning by disconnecting the charge wire, pressing on the accelerator to make it start, and I watched the clock for over a minute. Then a shift to Neutral, pressed the ignition button to shut the car off, checked that the parking brake was released, reconnected the charge wire, and off I went.
When I got to my destination, there were no warnings, no problems, and the car acts like nothing happened. No mileage noted, and the battery was fully charged. Of all the vehicles I have towed (about 5 of them), this was the easiest and simplest. I love this car.