Jeff, there are a few things you could try:
1) first, drain all the water out of the radiator.  The radiators on these
models seem to come filled with water.  This only makes your heat loss
problem worse.  Water is a notorious conductor or heat.
2) remove your front fan altogether.  This only tends to work at lower
speeds, though.  At higher speeds, you will have to find a way of
restricting the airflow through the grill.  I find that cardboard works, but
if you want a rugged look, try using diamond plate.
3) remove the serpent belt.  This has the added advantage of freeing up
plenty of parasitic horse power losses.  The steering also becomes more
"manly" and you don't have the alternator sucking all that "excitation"
voltage from your battery.  (you'd be surprised how long the vehicle can run
using just the battery for spark.
4) probably the fastest and easiest thing is to change the thermostat out.
You can easily fab up a disk that fits in the same place.  Many people have
found they can get a much higher temperature by just doing this mod.  You
may not even have to do 1, 2, and 3 if you are careful with your disk
measurements.

Good luck with your project,
TJim
98 TJ SE (252 deg)
90 SJ GW (276 deg - only once)