Before trying. Try another tankbag for space issues. I tried and tried but could get noting exept a little GPS case on without the bars being impeded and seriously reducing turning lock.
Added - Also you'll find pretty much any decent sized bag will obscure the instruments. sabuggger - I like tankbags too. But simply gave up. All I can suggest is find a localish stockist and go and try.
Not a tank bag but after I installed the RamAir I keep a spare T-shirt, shades, sunblock and a rolled up bonnie ht in the area where the OEM air filter was located. Much bigger storage space than I thought and the seat lock provides security.