If it were me (and it has been three times), I'd put the tall windshield on, I'd have Russell build me a long haul seat, I'd get the light bar if it doesn't have one already, and I'd install the powerlet outlet there on the left side below the seat. I have also enjoyed the heated grips, but other people often complain of problems with them. Maybe I don't use them enough to generate the problems. Another thing I've enjoyed is the locking gas cap. And then there is the little leather glove box that can mount on the windshield. It's handy for ear plugs, garage door opener, phone, etc.
I wish the bike had a tire pressure monitor, a tachometer, and a built in GPS, but it doesn't. I have gotten along without them.
I think the bike has plenty of power for a bagger. If I want more, I jump on another bike. Other folks do extensive engine mods, or try to fix perceived fueling issues by downloading available tunes. I like the stock fueling and timing maps just fine. I actually teach how to do this stuff, so it is not that I'm not familiar or capable to make changes. One thing I always point out to the students is that it is formally illegal to be messing with either exhaust systems or fueling and timing programs. I have two cars that get better gas mileage than the Rocket, so I don't need the lecture about how bikes don't pollute or use much fuel anyway. In the modern era, the Rocket does not meet the target CAFE goals any better than 99% of the current lot of cars.
Good luck with your project. I think the best thing to do with a Rocket III Touring is to get out and ride it. It's a great bike!