Question regarding refoaming a hot tub

[Mike32110]

So I fixed a bunch of leaks in my tub, ran it for 2 weeks, and decided now would be a good time to refoam it. I kept all the foam that I pulled out of it. To refoam everything (maybe 20 cubic feet?) would cost me like $500 if I wanted to buy a froth-pak kit. My plan was to instead buy some of this big gap filler http://www.walmart.ca/en/ip/big-gap-filler-insulating-foam-sealant-340-g/10026054?trail=SRCH%3Afoam+insulating&fromPLP=true&ancestorID=alldept&searchString=foam+insulating&moduleName=S0011&startSearch=yes&fromSearchBox=true&addFacet=SRCH%3Afoam+insulating and then stuff all the old foam back inside and just coat the outside with many layers of this. Does this seem feasable? Any other ideas? Thanks!

Mike