Some of the EV old timers think that these long distance rallys are a bit of a PR blunder.
They point out the limitations in EVs with things like wait times for highway charging & charger reliability/maintenance concerns in rural areas.
Also they force the need to maximize range (e.g.: by driving really slowly) which can annoy other cars.
People really want to say "see, an EV makes a perfectly good long distance road trip car", but short of a 85kWh Model S on a Supercharger route, I think we are far from there yet.
EVs at slow speeds in a city parade make more sense to me. People notice the quiet, and the lack of smelly fumes... Even better - take the parade indoors where gas cars are not permitted.