I don’t see height as an issue. I manage 3 machines, each at a different height for different reasons. At my school I have the 1000mm machine 30" off the floor because some of my 6th graders are pretty small and would not be able to reach the back of the machine if it was higher. The second machine, 500mm, is on a reworked “A/V” cart and is 38" up. For set up, this is a pretty optimal height for me. For the 750mm machine at the college maker space, I built a rolling cart with a torsion box table, set up so that a keyboard tray under the waste board is 30" high. The waste board is at 34" and a monitor on a swing arm is at eye level for an operator sitting in a typical office chair. When doing set up on any of the machines, I am usually standing and the height doesn’t bother me either way.
I considered and rejected the idea of mounting a fourth machine for my home shop under the left support wing of my table saw. I was going to put it on a pair of kitchen mixer shelf risers, but decided they were too weeble-wobbly for the purpose and that raises a different point you MUST consider.
If I was going to install an X-Carve on a sliding shelf as you are planning I would take care to build a very stiff, flat base, like a Ron Paulk torsion box. It doesn’t matter much if the machine is not level, but you definitely want it on a base that can’t warp or twist and you need it on slides that won’t sag. I’d hang a torsion box shelf from some heavy duty file cabinet slides and might consider a couple of flip down legs to support the table when the shelf was pulled out.