Hi @ryanpfromthedb,
Welcome to the community.
I have determined the ideal inner dimensions for the enclosure of my Pro XXL to be
59" wide
51" deep
39" tall
(see A few weeks with the XXL Pro)
48" wide won’t cut it, the official footprint is 50" wide and you need some clearance on the side for maintenance access (e.g. oiling the rails)
54" deep is plenty enough. You don’t really need any space in the back, but it’s convenient to have some space up front
27" tall may sound like it’s enough initially, but picture yourself reaching into the enclosure for any reason: that’s a guaranteed head bump. Also, lighting. And dust collection hose/boom. And future upgrades. Really, make it as tall as you can afford, you’ll thank me later.
That said, YMMV, there are lots of threads about this and no two enclosures are the same depending on taste, habits, budget, etc…