I see my trans temps rise to 205 to 207 when pulling my 6200 pound camper up grades. I also monitor my engine temps, and they too will rise to over 200 during these climbs. As long as you see them drop on flat roads, you're fine I'd say.
Running a transmission oil cooler for towing is a must if you want to keep the tow vehicle in good shape transmission wise, along with frequent fluid changes.
I also run an engine oil cooler to assist in keeping its engine oil cool.