You're in the right spot, for sure. If you intend to take out the 10' jon boat, you'd probably outta have a motor or a troller or something to move you around. I'd imagine it'd be rough to paddle a jon upstream for any period.
Anyway, I'd recommend Riddle Bridge (which is a lot closer to Ft. Wood than hazelgreen) and the area downstream to HWY 28. It's a special management area, so you can only keep 1 smallmouth, but the fish should be larger (in theory).
I usually fish around the HWY 7 access, Schlicht Springs access, Riddle Bridge, or even Adams Ford if I feel like driving. All of these spots have boat ramps (hwy 7 is a little sketchy though). You can find directions at:
http://www.missouricanoe.org/river-maps/gasconade.html
or even better, the google earth KMZ file referenced above by Gavin.
You can also checkout the Big Piney, which flows right through Ft. Wood and intersects the Gasconade downstream of HWY 28.