The Enclave has a curb weight of around 4780-5000 lbs, depending on trim level and options. With your 26,000 lb GCWR, that means the actual loaded weight of the coach cannot exceed 21,000 lbs, so you will have to weigh the caoch when it is loaded for the road and see. You also need to check the rating of the receiver hitch installed on the coach - it is probably 5000 lbs. In other words, you are at the hairy edge and probably beyond it once a few pieces of gear are stowed in the car.
Other than the weight, the Enclave is well suited for towing. See the instructions in your owner manual under Recreational Towing. If it is like other GM Lamda models (Acadia, Outlook, Traverse), you have to pull a fuse to prevent the battery from running down.