Does anyone else use a combination of these in their forays in the field?

If I'm out and about, but without a camera, wrong camera or it's not the right season or time, I will pull over and use the where am I feature on the GPS and mark the location in favorites so I can find my way back at another time should I see a promising scene. Unfortunately, my Garmin and TPE use different coordinate systems. I think there might be a feature on my Garmin to use another system, but I never tried since there doesn't seem to be a way to input the coordinate in TPE. Instead I have to visually find my way back using the TPE map to mark the same location for lighting, times of day, etc. Or, am I missing something in TPE and there is a way to enter coordinates??