Ok just had a look at the brand. as it didn't state it was fiberglass. yes this will work just fine

couple of things to remember. with water activated fiberglass you usually can only use it once. meaning once air gets to it, it will harden. found this out BTW. so when you wrap your legs, wrap in ONLY one layer otherwise you won't be able to cut yourself out. cut STRAIGHT down the centre of your legs (FRONT) I find this the best way as it make it easier to seam.

line the seam up, wrap some twine around the model and tie up gently. this will keep the model from dis-forming when you are putting in your foam. I found that you only need a bit as it expands 2X the original size.