Installing a ReallyEZPools Therapy Pool Partially In-Ground and need HELP!

Hello, We are installing a 6.5' x 12' ReallyEZPools Therapy pool in our deck which is now a winterized sunroom. This pool looks similar to some of the Intex pools with the steel tubing all around the top and 6 aluminum legs that hold it up all around. We live in Central Ohio where it gets very cold in the winter.

Here's what we've done:
1) Cut a hole in the deck, dug down 2 feet, made it pretty level, made an 8'6" x 12' platform out of 2x4's, 22" on center. We then filled the cavities with 3" closed cell foam.
2) We covered this platform with leftover rubber roofing and then 6 mil black plastic which comes up and attaches to the surrounding deck.
3) We plugged up all the air holes in the surrounding deck, and insulated the ground all around the pool with R30 fiberglass insulation.

After doing all that, we then put the pool into the hole. Our problem is that when the legs are completely stretched out, they hang off the platform in some areas, and it's impossible to make the platform any larger because we can't cut any more of the deck away. We're wondering if we can dump quickrete down the hole, around the platform, so the legs will have something solid to rest on when the pool "stretches" when filled with water. There's no room for a paver or anything. We could also dump small gravel or sand around the base, but we're wondering what would be the most solid.

The next question is then how to insulate around the pool once it's filled with water. Anyone use the Reflectix stuff and know whether it would work to wrap the pool with that, or should we just use fiberglass around it and hope it doesn't get wet?

The last question is, how do we get the decking up close to the pool all the way around? We have about 8" of open space between the deck and the pool right now which will need to be closed up. The pool sticks out of the hole about 2.5 feet (it's a 60" deep pool).

We've been working on this literally every weekend this summer b/c we had to put on a new roof, windows, insulate, drywall, add a closet, put on a new door, dig the hole, level it, insulate, etc. But the kicker is that the pool is longer than what we thought we ordered (we've had it over a year, but haven't installed it yet).

The other question is then, for a 2500-3000 gallon pool, how long will it take for a 100,000 BTU gas heater to heat the pool to 94 degrees, and do we need a larger pump than a 1/4 hp?

I know this is a lot of questions, but we're needing some expert help in this final push to get this thing installed! Thanks so much!