How about a 2008 or later Yamaha XT250? If you don't need to go faster than say 70 MPH that might do it. Top speed under optimal conditions is like 75 MPH. It's a total redesign over the old XT225 & much improved at that. And enough of an improvement over your 200 to consider.
Another option is a lowered DL-650 Wee-Strom with some off-road upgrades.
