"The cheapest and easiest solution would be to unlock the coupler while in the driveway before you finalize the back-in to the garage. It's not going to pop off the ball unless your tongue weight is entirely too low and that would be noticeable from poor towing behavior. I do that now that I'm towing with my jeep instead of the subaru. While the trailer and tow vehicle are on the same plane angled on your driveway just release the lock and then proceed to back the last few feet into the garage."
Thanks again for all your help! Problem solved!
Liz
