Solar well pump on / off control

Interesting Thread,
A few comments and thoughts;

Save yourself the problems of using pressure switches.
The problem is not the switch sensing small differentials.
Anytime you start/stop a pump on a long line, or some one flushes a toilet etc., you set up traveling pressure waves.
A switch based system 90% of the time will end up with short cycling problems.

Years ago I had the responsibility of a large campus with several water towers.
They were using small differential pressure switches with long mechanical delays to control pumps.
We needed to sense a foot of water pressure in a 100 ft tower.
The switches would do it but we had continual problems like the setting for summer would not work in the winter
And the delays were a continuing problem.

Anawa has a valid point, the wireless links are not going to solve your problem.
Buried lines have the same problem of what to do with the two receiver tanks at different elevations.
Buried lines are no fun to install in mountainous areas.
It can be done however.  
A 40,000 lb bulldozer with vibrating shank will knife wire through solid rock.
It will not be in conduit but you don't really need conduit when you are in rock and use the correct cable.

Lightning is seldom a problem with buried lines.
Lightning is mostly RF power.
The characteristic impedance of a buried line is way off what it needs to be to transmit lightning generated RF.
Plus, most wire now days is PVC insulated.
PVC has a significant absorption coefficient for RF.

All in all, the float valve method seems to be the best choice.
Make sure to have a good check valve at the pump and between the two elevated tanks.
This along with a delay before start, or as you suggested, require a manual start should work.
I would size down the pump such that it would not greatly over pressure the system when pumping against closed valves.
Looks like your are at or above the max pressure rating of standard PVC pipe.