My first “table” was even less than that: "RatRider" LR4 Build in the UK - #11 by FreneticScribbler
Just enough to keep the rail and belt holders (vaguely) in the right relative places. It’s workable if you put it on a flatish floor.
Certainly wouldn’t recommend using pine, I was being extremely lazy and used what I had on hand and didn’t need to cut. Your plan looks better. But I might have the worst LR4 so take my advice with a barrel of salt.