So more information on my test....
Today i cut the burned 3220 motor loose and tested the "good" motor. Turns out the good motor is roasted as well. It still turns..but under load it starts clunking...remember this motor only got to 209 degrees during testing. Its possible that one one motor partially locking could have caused the other motor to instantly fry.
So my run up mount diablo cost me $1000 in astro motors...ouch ouch ouch. But i do it for the good of ES RC prosperity.

Whats wild is at the start of this test i was very confident in this set up. As goodrum said from feeling how this trike roasted up steep short hills in the city, and the way it accelerated...i thought climbing even a 20 mile mountain would be a cinch. Many people agreed with me. I was kind of suprised that i smoked one motor..now i know i smoked 2 motors.
Miles...how should i figure out the right magical gearing number? i am kind of in uncharted waters and i think the right combination of gearing/cooling etc might work but the only way for sure is set it up and test. Even matt the 3220 expert has no idea what combination might work.
Remember initially when i thought about climbing pikes, multiple people told me the hv160 controller would be the weak link. It turns out the controllers never got over 107 degrees thanks to heat sink (will post pics later). The only way i know this is from this mount diablo test..may turn out on longer climb controllers will burn as well...but only one way to find out the way i see it.
As for the motor i either got to try lower gears or active cooling. A larger back sprocket will cost me $190...active cooling will cost about the same.
Since i dont want to climb the hill at anything slower than 35mph anyway i figure active cooling is my best option.
So the plan now is new nuvinci drive which shrouds the 3220 in heat sink, water cooling going through radiator mounted on battery tray, and a wireless thermometer to keep constant tabs on motor temp. Once motor temp exceed 190 degrees during the climb I will then stop test and invest in larger back sprocket.
I am not to confident on this first test because i will be running a single 3220 motor this time, and failed with dual 3220's. However active cooling and heat sink might be the ticket if my hunch motor temps are the only big issue for failure.
If when geared for 30mph and active cooling the motor still gets too hot its time to give up on 3220's altogether as a hill climbing option like lfp said....
rc motors just might not be up to the task no matter what gearing or cooling. I think maybe a giant pletenbourgh predator might hold up, and maybe i will try that next.
In any case I think we will know for sure how solid the 3220 is after this test.