It's OK to ask here but you should know that most here have Miata's and
what is OK for a Miata may not be OK for a Protege..

If my heat gauge approached "H" on the hills, I'd slow down a bit and
see if that helped.  Maybe downshifting would help also?

He might also try sending heavy stuff ahead via UPS to unload the car
some.

I've moved with my Miata for goodness sake...unless he's moving about
1500 lbs plus in a load and driving hard, he shouldn't really be
overheating at all in this weather (I'm in CT).

My guess is that his thermostat is beginning to stick.  If the car has
time to warm up slowly (highway), the thermo will have time to work
itself loose and allow coolant flow.  If he's on a hill, the change in
gravity (I assume you meant uphill!) may actually, depending on which
direction it's built, be holding the thermo from opening enough.
Also, sticky thermostats are really typical of cars that age.

If you're handy with a wrench and have 30 bucks to spare, rebuild/
replace the thermostat and flush the coolant system.  It's probably
about time anyways.  Or you could be lazy like me and tap on the hot
thermostat housing with a heavy wrench--this might knock some things
loose.

-r0ll