I know I have mentioned this once before. GPS Tools has become a great product and I think your implementation of our various suggestions has contribed to this success.
I think the final piece of the puzzle to making GPS Tools the best it can be and a home run is to add additional mapping layers.
I suggest Open Street Maps, Gmap (https://mappingsupport.com/p/gmap4-free-online-topo-maps.html), Thunderforest, USGS 7.5" (in order of priority).
The implementation of these layers into GPS Tools would make GPS Tools the finest product of its kind of any CMS platform.