If you get a chance, fill out your signature so we can see what mods you've done.
If you've modded the truck any, one of the most important tuning devices is a rail pressure gauge... and learning how to read it.
You've got a good start on gauges, but I'd say fuel pressure and rail pressure would be very helpful as well. Fuel pressure, meaning low pressure ( 0 - 30 psi or so) from the lift pump... allows you to see correct pump operation as well as filter plugging, adequate flow under hard accel, etc. Rail pressure being high pressure ( 0 - 30,000 psi gauge) that the CP3 pump is producing and sending to the injectors.
Those 2 along with what you have should be all you need.
Differential temp gauges are probably overkill unless you tow really heavy. Drive pressure becomes useful dialing in turbos, particularly twins, and can also be used to monitor exhaust brake performance.
I guess I'd be considered on the overkill side...
#ad
--Eric