... of cheap MiFi 3G routers from sw-box or brando, or use cheap but reliable brands like TP-Link or Huawei. I don't know where you are but these can be had for as little as $15 in Indonesia. You don't need fancy firmware and in-depth features, just connectivity over a short range.
Just use this network for an informative "Oh that's nice" role - nothing mission critical, but everything mission 'helpful'. Don't use it for live comms; but using it for advanced notification (before they get there and ask) in order to negate the need for live comms should be okay. Don't use it for anything at the scene, conditions will most likely be WiFi-unfriendly anyway.
With 2 on vehicles and 1 on each person (dump the casing and put the contents in more convenient/robust containers on a belt or something), with select 3G capability on each vehicle, you should be able to make a sweet logistics net.
Oh, make sure the enclosures for all your toys are fully waterproof. Things could get embarassing otherwise.