We are in the process of clearing ground for a 26' Intex ultra frame. Ground is leveled. We are on the edge of a field, so we want to make sure we do this correctly. Is it necessary to have a layer of crusher rock below the sand? We got many of the rocks out of the ground, but there is no humanly possible way to get them all, lol. We also plan on getting a Gorilla pad for on top of the sand. We don't want any large rocks pushing their way through. We are also going to tamp the ground down before we start adding any layers. I looked into the insulation to use as a barrier, but to me, it didn't seem any cheaper than the pad, and a lot moe work!