Need question answered on wheel bearing leak.........

Going on a trip tomorrow, went out to check the air pressure , etc. and noticed that one of my bearing site glass caps appears to have leaked since my last time out, checked them all and 3 ort of 4 seem to have leaked. Should I go ahead and remove the wheels and check and fill with 50 wt and go on tomorrow. only have to travel maybe 300 miles..........

Depends on how much has leaked out. Are they leaking from the rear main seal or out the glass itself or around where it meets the hub? If it is just a little bit, I'd go ahead and make the trip.

Find out where the leaks are and repair them...