Many years ago at Sun-n-Fun, I was looking at one of Van's factory planes. It had a cockpit activated tow release hook. When I asked about it, all I got was a smile.
Is an RV really practical as a glider tug? (I'm assuming that's what you're after.)
If we're looking at a broader selection of a/c, does the Experimental Exhibition category typically contain the towing restriction? If not, it might be worth a look. The restrictions in the category changed a bit, a while back.
Charlie