[Beaver]

With my 92 Itasca I regularly get 16-17, and occasionally into the high 18's. This is using 4th gear at or near the lowest speed that 4th will engage (45 -50 mph). Wind is my best friend and worst enemy. I've looked at the LeSharos and the Rialtas, but they don't have dual rear wheels, so I worry about tire loading. My Toyota is lighter at 6000 lbs, than the Rialtas, and the tire loading is considerably less, at @1000 lbs compared to over 1500 for the Rialta. I suspect the LeSharo is similar to the Rialta. They are definitely more aerodynamic than mine though. On Toyota MH websites I hear lots of unsubstantiated talk about 20+ mpg from these MH's, but I'm skeptical. I use the heck out of my MPGuino, and it really helps me adjust my driving habits on the fly. It also makes driving it more challenging and fun. Drafting big trucks on the freeway (at a semi-respectful distance (pardon the pun)) helps a lot, if they would just slow down for me.
As for getting better mileage in 3rd gear, I haven't found it to be helpful. First of all I would have to slow to around 35 mph to take advantage of the reduced wind resistance, but it doesn't seem to do any better that 45 in 4th. Most of the time traffic would not allow me to drive that slowly with any amount of comfort. If I ran it at 45 or more in 3rd my mileage would definitly suffer, and the engine noise would be really annoying. Let us know how you do with your Odyssey, BTW, is that a 4 cyl or a 6?