I have a handheld GPS, a Garmin GPS76MAP which I use for driving, sailing and kayaking. It takes a while to set it up for different uses, but it works well with a few exceptions:
Rough seas when kayaking cause it to stop tracking.
Toll gates on the Maine turnpike frequently cause it to crash and need to be restarted.
It frequently loses signals from inside the RV (because of the overhanging bed area)
MD