After a lot of research and talking to suppliers, I ended up for this use-case with a rover RTK design using the ublox f9P module, and using bluetooth to communicate between base and rover. Our team will test performance next week.
First, determine the fraction of the total area that each class takes up.
This is best done by just evaluating the total number of pixels with the given value, easily done iteratively. Perhaps by just reading all pixels into a long vector and subsetting that:
inputRaster <- raster(result_from_classification)
classifed_values <- values(inputRaster)