Well to close this out, I ended up doing the 4 90s. Yea, I know, more back pressure and more joints to leak. The slip on top was to fine tune the span. Wasn't room for the slide repair coupling, the 1 1/2" is HUGE. Estimates I got for doing this soup to nuts varied from 2K to 2.5K. Even though I knew where the leak was (generally) the leak guys said they'd still have to check the entire pool system. As noted earlier, plan to leave access as there are a lot (now lot more) of elbows in this area. Probably finish off the access area with some tan Trex decking. Appreciate everyone's help!
Don't have any way to empirically measure the change in back pressure, but the circ pump, with a little priming, started right up and flow seems normal. I was losing more sleep when I couldn't run the circ pump...the nightmare of waking up to an algeafest . Left side (pic) was first cut. Have that area ready for concrete. Have decided to keep "elbow area" accessible. The U bolt and 2 epoxied bolts (right side) will hold the joists for the Trex decking. Thx again to everyone who chimed in.