Clearly having a waterproof GPS is the best solution. For those of us who choose not to spend the big bucks however a large 5 inch touch screen Gramin 1490 can be had for $200 factory reconditioned. I bought one of these last winter and used it in all summer. It evan got rained on briefly before I put it in my tank bag,,,still working on internal battery.
I like the bigger screen..easier to see. the touch function works well with gloves...and I do like the low cost. I can trash 2 or 3 or maybe 4 for the price of a "waterproof" GPS.