I'm sure performance wise, it would make a fine tug and if built to be a tug I'm sure it would work flawlessly however, if you've never seen a 172 used as a tug up close you should. The best tugs are those that have tube structure inside, like Cubs, Pawnees, and the like. The skin on stressed skin aircraft tend to try to stretch, the rivets loosen over time and pretty much ruin the plane. Talk about smokin rivets... I'm not even going to go into the dangers of being a tug pilot.
I certainly wouldn't use an RV that I built to tow a glider, tugs can be had for far less money.
You're friend is right about flying sailplanes, it's the best flying I've ever done! Texas is a great place to soar as well. Many records have been set there. A couple of well known flight come to mind and have been written about, one from Texas to Gila Bend AZ and a couple from TX to Kansas. Careful though, it is addictive
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