I've ditched wearing underwear while hunting.. Sounds weird but instead of underwear I wear the form fitting baselayer leggings in the cold and under armor leggings in warm weather.
I do it for 3 reason, Moisture control, cut down on "layers", and tick control. I treat my baselayer with permethrin and I haven't yet had a tick get past the waistbands and the legging goes way down into my boot so i've had a tick down there.
The cutting down on layers is because it gets waay uncomfortable to have underware under my leggins and to pull the leggings and underware down when i need to pee.