Let's see some pics of custom tank builds

[Graveyard]

762 your nuts if you think this would be beyond your ability i think you've clearly proven that several times. For the half tank on the 06 you could do a nice dent with a lip like i did on my gixxer (check out the gxxer pics thread). or like you said you could do a full tank mod to your half tank, only think would be bending the metal to get it the way you want it, and possibly dealing with the airbox. as far as the vent it you cut out and replace your stock cap you'll want to extend the vent tube to the front of the tank and place a check valve like cycle gear sells for dirtbikes. heres one i just did, its easier to use a compression fitting then weld the tube.

i'll just throw in the pic of my tank so you know and don't have to search.