Would you consider a Class C that was used to tow?

I wouldn't worry one bit about wear and tear from towing. I'd worry more about rigs that sat extended periods and were only idled, without being driven a full drive cycle. This is worse than just letting it sit.

My rig has 450,000 miles. At least 250,000 of those are towing miles, typical combined weight is 22,000 pounds. I did do the timing chain preventatively around 400,000 miles, and that's it. Transmission hasn't been touched, and I've even switched to 100,000 fluid intervals.