Hi, Mandy. Welcome to the board.
Sorry you're going through this. We had a similar situation with a 5-yr-old springer spaniel that we inherited when her first owner died. She was huge for a springer--about 65 pounds when we got her and 55 when we got her down to a good weight for her size. Both hips were severely dysplastic and we decided on getting both replaced. The second hardest part about the surgery was the week she had to stay at the hospital for initial healing--we worried about her all the time. But the very hardest part was keeping her still for up to 12 wks after surgery--and keeping them still is critical to good healing. She had so much improvement after even just the first surgery that she wanted to bounce around and run in the yard. I finally resorted to tethering her to my belt...for what turned out to be 22 wks in total (recovery for the first hip replacement was 8 wks, then 6 wks to recover from back surgery to fix damage due to the way she carried her weight when her hips were so sore, then another 8 wks the second hip replacement). Because tethering was so effective at keeping her still, her recovery time was cut to about 1/2 what they thought it might be.
The results were like night and day! She was a stoic girl, so we never really knew the extent of her pain till suddenly she was moving without pain. And move she did! All surgeries were done by the time she was 6 and she lived till the ripe old springer age of 15, so she had plenty of time to enjoy her pain-free joints.
Things to do to give your boy comfort in the meanwhile (and it sounds like you're already doing most of it): keep his weight on the low side of normal--more weight stresses the joints; the dietary supplements (glucosamine/chondroitin, etc) can be quite effectivel; moderate exercise--swimming is wonderful if you have a facility near you; pain meds when needed. Most of the pain meds are NSAIDs and require periodic blood tests to monitor organ function. We never had it available, but I know people who also use accupuncture and chiropractic with good results for managing hip dysplasia.
We had to travel 200 miles to Minneapolis to have the surgeries done at the U of MN Veterinary Teaching Hospital. A university with a veterinary school is usually a good place to find services--in our experience, they've been pricey but well worth it. They deal with so many more cases each year than any one veterinarian clinic can so they get lots of experience. So even if you have to travel some, check university towns out.
Good that you have pet insurance that covers dysplasia! It cost us about US $2200 per hip back in the 80s--I'm sure the cost has risen since then. We paid for it out of pocket, but it was worth it.
Good luck with your boy!!