Hey champs387,
That tube that the pass seat hooks to is shorter as you've seen, I'm going to make a good metal bracket but for now its being held by zip ties, for the underneath I trimmed the stock bottom enough that I could bolt the new tail through the stock underneath for now, I plan on making a good full undertail for it, for now its half stock plastic and a peice of aluminum that I cut to fit for the undertail, the front mounting holes for the stock tail section is on the side and the new ones are on the top, I was going to drill holes but it lines up right on the weld, so I used velcro and zip ties for now, for the tail light I made a bracket that I bolted on the inside of the stock plastic trunk space and bent it to make the correct shape I needed to mount the tail light to it (kind of a U shape bracket), this took alot of time! And as far as the front seat, there is no extra gap for the battery access, it's cut just like the stock one, it fits perfect!, and as far as stirdyness goes, you can grab the tail between the light and the pass. seat and if you move it around the whole bike moves, there's no play, it's really strong, since I used nuts and bolts not like the stock little plastic clips!:fact I'm glad you like it, I'm going to make stronger brackets in place of the zip ties but for now its really steerdy, I took it for a good test ride today and everything holds up great!, I'll post more pics later!