Why not a used 250?
I myself have a DR200 and it is SLOW.
Even around town it feels slow, people doing 50MPH+ in the right lane, while I'm hitting 45mph in top gear.
If the DR200 had a sixth gear, it would probably be ok.
I wouldn't even want to try it on the freeway.
Maybe an XT225 would fare better, with slightly more CC's?
If I could do it over again, I'd get the WR250r.
Yeah, it costs some money.
But it's fuel injected, can cruise in the 70's no sweat, large after market, etc.
It's a bit tall but can be lowered with a Yama-link as far as I know.