Aside from the foil underneath (which does make a difference, IME) you could build a baffle from aluminum flashing to hold the heat near the pot on the sides (ie, a cylinder about 2" larger diameter than your pot, somewhat shorter than the handles). Depending how that sits it might need some slots on the bottom so the flame gets adequate air, but it should help apply the heat to the pot.
The heat stick idea still applies - no reason you can't combine 1000-1500W of electric (suits a 15 amp 120V outlet just fine) with your gas burner. I'm a bit more cautious than AnOldUR, and would probably pay the gas guy to go over the stove to optimize the heat output rather than messing with the orifices myself.