Part of the reason the tank looks long is because it is. It's not a stock 500/550 tank so compared to the short seat pocket, it will visually unbalance the bike. Doesn't bother me though.
As for your rear loop/tire conflict, the longer you make that, the more the upsweep creates space for suspension travel. Som possible options to avoid the conflict:
- Drop to a 17" rear wheel
- increase the shock length
- sweep higher/sooner
-leave the hoop "open" underneath for the tire to pass thru it when compressed suspension
Realize if you alter the wheel size/suspension length, you are altering the steering geometry. It's not a huge factor, but it will behave mildly different so just plan for these changes.