Hi, I want to mount the Airtop onto an existing 19" fan-plate. The integrated footstand will be in the way of the airstream. Can I easily remove it to machine holes in it or just replace it with something else? Thanks for the help.

You cannot easily remove the foot of Airtop. It is part of the chassis which is a single die-cast part.

You can get excellent results by placing the fans above Airtop and blowing air downwards.
You can get good results by blowing air onto the side of the airtubes.

Both ways work because the very large heatsink can dissipate heat with very low airflow.