Usually bloating is from improper digestion and sadly I haven't heard of the proper treatment for that. Your BP probably has weakend internal organs from spending the summer in that overly hot enclosure and poor husbadry. I would do the following:
1) Give him a bath using water that is exactly room temp. I think it's all too common people use water that is too hot, remember if it feels warm to you the it will be too hot for the snake. While he is in the bath try rubbing his swollen belly bery lightly letting him slither over your hand. Do this for about 5-10 minutes every 4 days or so.
2) Make sure his temps are SPOT ON. As well as humidity. If it is a digestion issue then he WILL need a proper gradient that he can choose to move around in and choose the right temp to digest the meal.
3) Feed him smaller meals for now incase his organs are not strong enough to handle such a large meal. I woul record exactly when I fed him and when I offered food. You can post that info on here too. I would personally only offer food every 5 days and again, small meals.
4) Get him a really nice hide that he will use. Another user made me aware of Boots and Barkely water bowls for dogs at Target and they are amazing, most of my snakes love them. He IS stressed out beyond belief right now. The move, poor care, frequent handling, baths, all of this adds to stress. High stress doesn't help an injured body.
This is just what I would do. I am by far not the most experienced person, this is just what I would do if I couldn't take him to a vet.