I understand what you are trying to build now. I think getting the table flat will e a challenge, nothing wrong with it though, but you are going to be facing a bunch of stacking / compounding errors that will add up over time - you’ll eventually probably find you’ll need to have a spoil board that you surface to be level with the machine.
Since the table is going to be wood, it is going to change size / flex a little with changes in humidity. Also, the machine itself is made up of a number of parts that are 3d printed, and while pretty accurate, I know from my own 3d printing experience, that you need to build in tolerances. This along with the fat that all screw holes have a little bit of slop in them means your gantry and rails are going to have a little error in them as well.
I guess what I am try to say is that, even if the table is completely flat, you might have a difficult time getting the machine trimmed to the perfectly flat surface of your table.
However, no reason to not go for it, the more accurate you build the surface, the easier it will be to get your machine dialed in.
When I built my flip table I built it very simply - I had a 3/4" threaded rod run through the middle, and then build a 3 layer 3/4" plywood sandwich around the rod so the table would pivot around the threaded rode. I used screws so I could take it apart if I needed to. However, this is just to put tools like a lathe and sanders on so perfect level was not a concern for me.
Good luck interested to see how it turns out!