Ken, we had this exact situation on our recent trip to Rayford Crossing. Going south on I-45, there was wreck after wreck. The rain was coming down hard and the ground fog had rolled in, severely limiting visibiliy. Many cars hydroplaned and either ended up in the median or off in the outer ditch. We saw more than 40 of them. While admittedly I had an air pressure problem that was worrying me, I really slowed down because I didn't want to be too close to the cars in front of me. I couldn't believe the number of cars, trucks and even other RVs that passed me with no lights on and doing 70+mph. I always worry about the differential between my speed and that of the rest of the traffic but there was no way I was going to drive that fast, under those conditions.
2000 Georgie Boy Landau 36' DP
2005 Saturn Vue toad