DVC hooves

I recently ordered their Large foam cloven hooves for a commissioner and have a question. Although first let me say I have no problem with the quality of their product (their stuff is always amazing and as I have said before their customer service is equally so.) So.

Anyway, my thing is I didn't realize just how large they were going to be. I always try to measure before buying (although this was something the customer picked) but it seems like stuff I order is often times larger than I anticipate. So, it says it fits all sizes of shoes and I feel like it -will- glue to the shoe I plan on using but it seems like there is an awful lot of space (gaps?) and not sure if that's going to be a problem (or not) Like, I'm not sure if once the bottoms are glued on and I add the fur it won't be noticeable, or if I should add some foam? Basically, has anyone used these before, and added them to shoes, and if so did you add foam or anything in addition and if so to that where?

Help with this would be super appreciated! This is my first partial commission so I want everything to look nice as possible. Once again, the product looks great, just looking for the best way to install it. :)