Three questions you gots to ask yourself:
How comfortable do you want to be while you're riding it?
How far/fast will you likely be taking it?
How serious are you about taking it on unimproved roads?
With those three questions in mind, consider the following smaller, lighter packages.
Kawasaki Ninja 250, new ones go for $4k +, used ones 1.5-3.5k. Less than half the weight of the ST, can do freeway speeds, dirt cheap to operater, smoother than any thumpers. Standard ergos, sportbike appearance.
Suzuki GS500, Kawasaki Ninja 500 - A bit heavier than the Ninja 250, standard ergos, cheap, reliable.
Triumph Scrambler - heavier again, unpaved road worthy, easily handles freeways, way cooler than a Versys, WeeStrom, any DP bike, any adventure bike.
250-400cc DP bike: light, definitely dirt worthy, some can get ya around on the freeway, some can't.
TW200 - ultimate plonking around on the trails, poking around town bike. NOT freeway worthy, but if you aren't interested in tearing up the trails, it can go just about anywhere. Very much a proven design.
Finally, you may want to consider a 150-250cc scooter. Look at the large wheeled one's, along the lines of the Honda SH-150.