Using Reach RS in rural areas and EM integration

We are looking for a cheap GPS solution to integrate with an EM38 Mk2 soil analysis system we are using on farms, sometimes in areas with little or no mobile phone signal. Is it practical to consider Reach RS in these situations? Is there a way we can establish positions using 3G/4G until we lose it, then rely on satellite from there?

Does anyone have experience in how to connect the Reach RS rover data stream to the EM logging data so they are synchronised into one data file?

Yes, its Reach RS is always practical in my opinion. I dont know of any other RTK sub cm device that uses less gear to do a survey job like this. You only need a phone with 2/3/4G and a RS unit.
With ntrip this should be possible.

Not sure i can help you with that EM sync thingy