I'm enjoying this thread!
Personally I have a small solar/battery system (and my fiancee just bought her own). We field-tested it for a week this summer and were able to comfortably power a base station, several portables, and several cell phones. That's in addition to a decent amount of stored food, propane, water, individual equipment, and the means to protect all of it.
We went the P25 route for our private communications. AES is standardized across manufacturers so it's not a problem for subgroups to choose different equipment. Our gear is all EF Johnson and Motorola but integrating Kenwood, Tait, Harris, or BK gear is trivial. Subgroups get their own keyset that isn't shared beyond that group, along with a shared keyset for interoperability. A nice side benefit of this is that it forces you to get organized before needing to use the equipment for real.
Rather than relying on fixed repeaters, I have a simplex repeater that can operate off any of my portables. It will pass encrypted traffic and is small and light enough to carry and drop off anywhere. I need to set up a second unit and work on an extended battery.
Something else we've implemented is TMS. A quarter-second data burst can convey complex information while being nearly impossible to DF, and it seems to get out a bit better than voice. Between encryption, data, low power, transmitting while mobile, and terrain masking, it's not too hard to be miles ahead of 99% of potential adversaries.