I currently mash and ferment in the one vessel, separate grain and distill the finished wash.
Hitting strike temp for my grain is OK with the boiling water from the still, preheated vessels and short hose. The issue is the grain separation. Can be done but is hard work and labor intensive if no dewatering equipment is employed.
If using corn, you would want to grist it, not mill it to flour like consistency. Corn is cheap and the losses from non conversion/wort retained in the grain are minimal when you begin to look into liquid/solids separation equipment. It can be done by hand but trust me, it takes hours and is tough going.
Is there a reason you want to ferment on the grain? Do you have another grain with husk in there too? If not then you need to be looking at some separation equipment (+$20k).
If you get good liquidization (from holding high temps for the first enzyme addition if using liquid enzymes) then this will assist in your return but you will still have a sloppy mess to dispose of regardless.