My question is, I now this machine is heavy, but does anyone have experience with two of these tables (or something similar) next to each other being a sufficient base?
Those plastic top tables will not work for such a heavy machine as the SO5. Some people have built their own out of 2x4 or 2x6 and others have bought the Rockler and Kreg ones that bolt together. As @WillAdams indicated those just are too unstable for such a heavy machine with a lot of momentum moving around on top. Another source is openbuilds.com if you want to build a custom table and/or enclosure out of extruded aluminum .
You need a rock solid table for success. It does not matter if you buy or build your table it is a good idea to have 2 way locking casters. The reason for the casters is to make the machine portable for cleaning and maintenance or if you decide to do tiling. Once your machine is planted on a substantial table without casters it will never be moved. That can be a real problem for maintenance and for tiling options.
In another post you’ve talked about the foam mats you put under your machine to help with leveling, vibration & even noise (I believe). What would be the process of me (now) putting those under my S 5 4x4?! Basically I’m wondering if me a buddy of mine can just lift the machine (one end/corner at a time & slide those mats underneath?! Or will have to disassemble everything, put the mats under & then reassemble everything. Basically I’m just asking if it is best to take everything apart, or if it can be done without having to do that, but also won’t mess anything up??
I would lift one edge at a time, rather than one corner — that way you’re less likely to torque anything out of square — assemble the mats, lift one side, slide it the assembled mats under, then lower and shift/adjust things until everything is positioned as need be.
Then, once the machine is on the foam and positioned where you want it (I like for it to be up against the front of the machine for cutting vertical joinery) you can check for square and if need be loosen all the hardware and re-square.