Gantry Width Impact on Rigidity

I have a line on a few second-hand machines, including a 2019 5x10 Pro, but am apprehensive about the gantry width and rigidity. I’d be marrying it to the 6.5 kW Hiteco spindle. Assuming table rigidity was confronted, to what degree will the gantry width be a liability, mindful that my application will include Z axis extension to reach below the table top.

Alternatively, there is also a 4x4 possibility. Speaking to the gantry still, might shortening the cross members to deliver a 3x4 have appreciable impact?