Doable? Maybe. Overweight? Probably. Towing in the mountains? Slowly, very slowly.
At 4700# empty our new TT came in at 300# over the "brochure" weight. Dan covered the numbers, and to add to richardwise's comments: I came out of an Envoy rated at 5100# towing a 3850# 21SSO Starcraft hybrid with DW & me in it. And every time I went up a hill I wondered "Who put the boat anchor out?" No way would I have tried it with the new TT.
While they may have similar engine ratings, the Traverse will be running much higher RPM's to get there.