You've never ridden an xr650r then, Tops out around 108mph, Large gas tank that will literally last all day when full and the stock suspension is soft and feels good on the road, Get some 17" supermoto rims & tires and a big brake kit for the front and it's basically a road couch with a lot of torque.
The same can be said for the drz400sm.
Plus if you don't like the soft suspension just got get it set up, Competition supermoto's usualy have stiff suspension like sportbikes.
Supermoto's are just as road capable as any other bike, You just have to get a good setup.
As for valve adjustments and all that, You're thinking about motocross bikes and competition bikes like ktm that you rebuild every few hundred hours, While they can be ridden on the road it's best the stay on the track, Where they were intended to be.