I finally blocked the lower grille on the Honda using Corrugated Plastic and duct tape. I also looked up towing in the owners manual and it gave a distance that it could be towed (EOC) after the transmission had been run to circulate the fluid. I'm keeping the mud flaps on for now.
So, on my short almost daily run where I would get 22-24 mpg (best), I got 26.2 mpg (ScanGageII) for both runs. Highly unscientific, but obvious to me. I think these were good changes.
Duct tape changed to blue painters tape. The silver duct tape on a silver truck and car looked a lot better, though.
The owners manual says towing with front wheels down for 50 miles at 35 mph. My EOC is at 35 or less, so I "assumed" it would be ok. Since you people are the experts, I'll limit myself to Engine On coasting.
Yes, I knew about cleaning off the duct tape, but normally acetone works, as it did this time. Hope there isn't a problem with the blue tape. Just for info...naptha works on almost all other tape residues/glues, but not on duct tape.
With the temperatures in the 30s I blocked off the upper grill as well. That was too much. Temperature went over 220°F, so I had to stop and pull out the foam blocking the upper grill. Next experiment will be to block the upper and open the lower to see what the water temperature does.