I wouldn't be concerned for transmission cooler. Braking capabilities and hauling up hills or into a wind worry me more.
Your commitment to not being in a hurry is also important.
I wouldn't want to tow that on a regular basis but for a one time easy does it, probably ok.
Would it make more sense to hitch a ride on a bus and rent a truck to tow it home and save the wear and tear?
2015 Canyon SLT, Copper Red, 2WD, CC, SB, V6, Tow, blk leather, factory spray liner, safety pkg, generic roll up bed cover.