If I set a 160mm gap bottom of top 2020 to top of middle 2020;

All the rods and the leadscrews are about 3 to 5 mm too short to fit entirely in rod clamps or  bearings.

Bearings and clamps both on bottom side of base / top plates.

I suppose the only thing I can do is increase gap to 165mm?

but what will this do down the assembly process.