I cant see how this would help getting better accuracy of your geotagged images. Flying more accurate doesnt geotag your images better, unless you fly free handed and banging your TX stick continuously.
Your onboard controller/navigation with stock gps should fly your drone within few meters of plotted route stable enough.
So, unless you need your drone to fly with few inches accuracy, for reasons i cant come up with right now. PPK would be way to go and rather improve accuracy in other areas.
RTK as i see it and for the mission explained, this would introduce more things that could go wrong and worst case, degrade your PPK accuracy with more noise. But i`ve been wrong before and if someone knows something i dont, please tell and i would go back to playing with my Lego 
But this should probably get you going with the LTE thing