Mine is on a table made from plywood and lumber (2x8’s for legs, 2x6’s for the top’s frame and 2x4’s to stabilize the legs) and is on four cheap casters. I have no problems with sturdiness. That mobile workbench is probably more than solid enough.
My table is just barely wider than the glowforge (happy coincidence as it was built for something else) but it is probably a foot or more deeper. I find I spend a lot of time in front of my unit and having space to fiddle with stuff, set stuff, etc… is very helpful. If you had a table/bench nearby, that would work just as well. I know other people have slightly short (width-wise) tables and I haven’t read any complaints.
If you have a Pro you do have to consider how you will support any material protruding out the front and back making a deeper table helpful.