There is unlicenced spectrum where encrypted traffic is allowed (900MHz, 2.4GHz, 5.8GHz) why aren't those adequate for these experiments?
(Which is why spectrum is much more valuable and there aren't unlicensed bands.)
33cm ham band, up to 500kbps, tons of range, especially with yagi/directional antennas, even in a metro area the size of LA. The sad part of this project is that it never took off.