as much as i like the bike, i hate the seat.
i built a 26" muscle bike and ran into the same problem. the standard banana seat just looked too small. i wanted the down tube for the seat and the sissy bar for the seat to be paralel. (cause it looks so much better, and its alot more comfortable)
i tried adding a custom layed back seat post to correct the problem but it wasn't quite long enough.
it wasn't until i found this extra long banana seat, that things started to work themselves out. if ya look close, i also re-drilled the seat further back. (filled the old holes with 8ball bolts.
now i dont have the sissy bar jamming into my back.
to each there own, but its something to think about.
bout the bars, you might consider pinning them (set screw in the kneck etc) like ya mentioned, with that much leverage it wont be long before they start to move on ya.
nice ride.