I have a folding chair near the end of the machine for tool changes.
I suggest using extrusions from 80/20. You could easily build up a nice 4.5"x4.5" block and bolt the machine on top of it. These extrusions are easy to tap so bolting the machine to the extrusion would be painless. It would also cost maybe $100 including shipping, less if you bought the materials on eBay.
ShopBot Details:
2013 PRS 96x60x12 (Centroid upgrade)
4hp Spindle
12" indexer
Aspire
Rhino
Fusion 360
Ferrari 360
Prusa MK3S+
Prusa XL multi-tool