I decided to go with the O2Link Router with a 7.8 db gain mag mount antenna. This should let us network in a normal caravan configuration on the highway.
Are you planning for one in each vehicle? If not, the wireless cards in the computers in the vehicles not equipped the same way may have trouble communicating with the equipped vehicle even if they can receive a good signal from the router ... for this to work, two way communication is needed and the weaker transmitters in the wireless cards could get lost in the mud. I would be interested in knowing how well this works for you ... as you can tell, I have some doubts about this setup.