I use a Garmin etrex legend. I'm confident that it is giving me mileage good enough for any purpose I have. It does show a meandering path on one of the windows...quite well. With the gps I found that I don't travel as fast when I'm trying to, as when I forget about traveling fast and just get into a zone and develop a rhythm. Then I go much faster. I like my gps. I also use it to mark good fishing and exploration spots.
As for varnishing...I always wait for several months for the epoxy to cure before varnishing, or painting. That is a two edge sword because I do get a few scratches that I have to take care of. Vicious circle.