Well, we should put our thinking caps on first. I'm no electrical engineer, I hold no PH.Ds, so I propose this....
Not sure if we're on the same page with the 1 gauge, multiple temperature sensor monitoring. A lot of the short sweep electric temp probes Autometer have a 1 wire sensor. Run each probe's wire to a rotary switch for example, then the gauge gets hooked up to the rotary switch and can receive a signal to whichever switch position correlates to whichever temperature probe.
You cannot "monitor" more than one thing at one time, you simply switch the dial or flip to another position to see what the next probe's; wherever it is screwed in, temperature is. This is just a bypass to avoid extra burden of gauges if that is your preference.
The personal preference part is, "Do you need to see what the diff temp is?" I would assume that would be a YES in this instance, so you either buy a whole gauge just for that, or you can simply use my "proposed" method of obtaining a measurement while cutting down on costs and clutter...., again, personal preference. You get into ISSPRO, and all the other guages and I'm not quite sure how their wiring is. The downside is, until you "flip da switch homie" you won't know what your coolant temp is when the switch is positioned for the engine oil.
I hope this was a little more clear for Dr. Dre, his F650, and yourself.