Thanks for the response. That's what I was afraid of. I did get a reply from Skinz and they said they were not sure that it would not work, but thought if I was able to make it work it would require a bit of modification. They didn't provide any dimensions or pictures to go from.
Impulse doesn't sell a seat for the Apex, but they have one for the Nytro.
I do have a flatbottom Boss seat that I will have to cut foam out of to make it work, which is what most people have been using/doing, but it doesn't leave much cushioning in the seat. I was hoping the Skinz would work so I could sell my Boss, and not have such a hard seat. Oh well. It'll work.