Welcome to BPO.
I'm going through TPLO surgery right now for my 1 1/2year old Newfie. We are into week 7 of 8 week confinement. Probably within 2 weeks we start all over again for her second knee so she will be out of commission for a total of 4+ months. She has a brother of the same age.
We converted our garage into her hospital long-stay unit. That way we didn't have any stairs to take her out for potty breaks. We also put up a barricade to keep brother from bothering her, but they could still be around each other. After a few weeks I would let him sleep with her at night.
The sling works well and as Damage mentioned, you don't need to hold the entire weight of the dog, you are just adding support and taking some of the weight off. As he starts using it more, the sling helps in case he slips and to keep him from going too fast. I quit using the sling on Sophie after about 3 weeks and probably could have stopped earlier. Then I used her leash to keep her from running.
It is a long process and sometimes you think it will never end. I was seriously thinking of waiting to do her other leg to give us and her a break. Let her be a dog again for awhile. But she has recovered so well the fixed leg is functioning better than the other. Now when she struggles to get up it's because of the remaining ruptured ACL. We decided not to delay. Get them done and out of the way so by late spring and the rest of her young life she can function properly and pain free.
Good luck with your big guy. You'll not find a better support place as you go through this step by step.