Hi,
Just wanted to share my experiance...
When my 2009 R-21EC was delivered, the dealer trailered it down from MD, directly to my home. He stowed the mast on the v-birth for the trip. While we were going over the boat, we installed the mast and propped it to the left, opposite of John's '08. Once we looked over the boat and he briefed me on the equipment, we headed off to the ramp for sea trials. Mast stepped for trials and then propped for the drive back. We had absolutely no problems towing with the mast propped to the side.
The next weekend, was pulling out of the drive way and heard something from behind, I looked in the review mirror just in time to see the mast come crashing off the roof, one cable still attached and swinging the mast back to the side of the boat. We were lucky it landed on the rail and didn't damage anything. It was very close to contacting the side window, perhaps one of the hatches on top.
As a result of this, I will not tow my boat with mast in place.
Something else to consider; just about every time we launch/retrieve, there are always on lookers who are very interested in these neet boats. I haven't had to ask for assistance from any of them yet, as always have my first mate with me, but if I find that I do need an extra hand, I'm sure one of the folks at the ramp may be willing to assist just to see the inside.
Good luck,
Bri