Do you need to pull from both valve covers when you use a belt drive vacuum pump or pulling from one side good enough

no one cover will work just fine..

1x side is enough, but I'm sucking from both.

racepak

One side only, install the bypass close valve to the suction fitting also. Don't suck dirty unfiltered air through the motor

If you are on gas it is ok to pull from one side but I have found on alky that pulling from both works better for removing the moisture.

How warm do you let the motor get? I run one hose to the valvecover, motor sees over 200 degrees often on the return road, no problems. I believe it boils off as much or more than collects in the little tank.

I just pull from one side also and I'm on gas.

I run E85 in my S/P car, I got a lot of moisture on the first motor with no pushrod oiling. I swapped motor and added pushrod oiling and spray bar oiling and I had to improve the baffling under the suction fitting in the new valve covers with the spray bars to stop the massive oil sucking into the breather tank
My car has no radiator, it has two small oil coolers for the engine coolant so it runs warmer now than other cars, I've seen 230 F when I shut it off in the pits after a run that started the run at 160+F , it is a 1/8 mile track in central OR with 80+F outside air temps. in the summer

I run my coolant temp around 170-180 and the oil temp will get over 200 hot lapping. On mine the moisture seemed to collect on the side without the vac line. I discovered it one time when I pulled the valve covers with the engine hot to check the lash. Vac line cover was dry.

One pickup point is fine on Gas for sure. Alky not a clue but don't see why you would need a second.