the 5.5 clark tank will require cutting of stock plastic. Neither aftermarket IMS, Clark etc will fit under Fullbores. Can only use stock tank with fullbore.
The Clark 5 gal style is requires to cut the plastic & looks hella ugly to me. The IMS 4 gal or is it 4.5?? I forgot, but that's what I have and does not require any cutting of plastic. Gets all around Glamis just fine. Check the pic in my sig.
That's wat dune adventures are made of, sounds like you got lucky. I hit a witches eye on a Glamis night ride and wasn't that lucky. I'm ready for dumont raxorbacks this coming weekend though. Some cool Halloween stuff going on down there!