I have specialized as the FD 40M CW op for about 25 years. Polarization is a big help with inter-station interference. I also use several antennas with different take off angles for different target ranges. The NVIS is best out to around 200 miles. A dipole at 30' is best from around 200 miles to 600 miles or so, and a vertical with elevated tuned radials for longer distances.
I have a power splitter so I can feed them one at a time or multiple antennas and still show the transmitter 50 ohms.
This is from the Midwest. From eastern Oregon you probably don't have a lot of stations in the 100 mile range or so, and the NVIS might not be that useful.
That sounds like a good idea. I've got a surplus military mast of the type where you assemble sections and then have to rais it to a vertiacl position. A telescoping mast sounds like it should be easier...
For Field day, we've found it preferable to have a mix of horizontally polarized and vertcally polarized antennas to reduce the interferenced between stations.
Your fuel-cell powered FD is just a mildly updated version of what I remember of my days with IRAC (Irvington NJ Radio Amateur Club) more than 50 years ago. We used multiple 3KVA gasoline-fueled generators for our 3-4 rig Field Day station, along with a lot of "festoon" strings of 115V incandescent lamps along the paths connecting the tents. Maybe you should try to get permission to use a wind-power site next year (as you seem to be in CA, there should be some not too far away). Of course, you might have some Doppler modulation effects from the turbine blades!
I'm still Advanced class, W4LGN, but inactive these days.