Thank you for the suggestions and help on this question of installing the Canon ipf 8400 on a flat surface instead of the stand.
If I go this route, it will be sitting on top of 4 flat files. The flat files are not stacked though, they are on a heavy duty (7500 lb capacity
steel shelf from Home Depot).
I have setup the shelf unit so that the printer would sit inside a 28 inch vertical opening. I could make this vertical shelf opening be up to ~ 34 inches if needed. (from this thread it looks like the height of the printer unit, without the stand, is ~ 24 high, and then I need some clearance for the top of the printer to swing upward and open).
I have not yet unboxed or moved the new printer and I am willing to go with "Plan B", that is just install it in the studio on the printer stand as designed, and then get rid of some of the furniture in the studio to make room.
Issues with the print output getting stuck on hitting a hard surface, versus falling into the ipf 8400 catch basket do concern me, however this might be mitigated by monitoring the print job in person (something I would do anyway) and / or designing some other catchment system for the output print.