Is this a completely stupid idea? No, it's fun... Something to do when there's no wind for sure.
If not, then what kind of foil would be best for this activity?
. Liquid force impulse (or similar size wing)- 54-82cm mast. You can use for kiting when you get some wind.
Tips for doing this?
Tricky if done improperly, easy if done with a driver who knows what they are doing.
My technique for strapless- put foilboard at 90 degrees with water (foil halfway out of water), 90 degrees to boat (like a wakeboard start) holding foil on rails with one hand and 2x feet, rope in other hand.
Putter slowly till rope engages, idle engine for a second till foiler starts moving a bit, Re-engage engine at slow putter when they start moving (reduces yank on their one hand). You want to keep them moving, if you get slack in the lines, the foil will come off their feet. At this point there is enough pressure on the board that they can get both hands on the rope. Once they have both hands on rope, slow/smooth acceleration (less aggressive than wakeboard), till you reach good speed, then hold.