Electric fan controller

Back to Younggun's original post if you don't mind, I've got some similar issues. I recently switched from a single fan that I hated from the moment I installed it, to a dual Spal set up. The original fan was wired thru a Flex-a-lite controller which really worked pretty well. When I installed the dual fan set-up I wanted to incorperate the same controller, which was only made for one fan, so I ran the drivers side fan thru the controller, and use a toggle on the dash to accuate the passenger side fan. So far the set-up works well with the single fan on the controller taking care of the lions share of the cooling, and the toggle accuated fan picking up the slack during high heat bumper to bumper traffic situations.
My problem is when I turn the car off, the fan on the controller keeps running for way to long, it stayed on for over 20 minutes the other day when I was at my buddies house. This has a pretty big (bad) effect on my battery.The reason is because the thermo sender for the controller is in the intake manifold and it does'nt cool off very fast. Younggun said he had a bung welded to his radiator for the controller's temp sender, is that the only way I can use my current setup, or is there another place that I can mount my temp sending unit so that the fan won't reflect the temp of the block, but the temp of the water inside.
thanks- pauly