I filled my van mounted system from a well for a while, also had a 40 40 ro fitted,regarding the pump I had to purchase a well pump,this was required as the pump could pump the water with enough pressure to force water through the ro,if your pump is similar you will be ok
The other thing to watch is if you have a lot of rain the water will be filling the well quicker and will possibly not have time to settle this will shorten life of you pre filters.