Been there. I have a Held bag, bought at the BMW dealer, after looking a several. It comes with a set different of tie downs, and I have figured out what works. There is a pic somewhere else on this site (http://www.v-rodforums.com/forums/showthread.php?t=2572). I have a accesory socket, that I wired to my battery tender, to power stuff I put in it. Took a 500 mile trip last july. No problems. I worry about scratches, but so far, so good.
Yup, I can see the speedo just fine. The bag has an expando zipper. I expect that if I opened it up to full height, it might be a problem. I am concerned that the bag will mess up my stick-on flames, though. I'll cross that bridge when I come to it (in a month when I pack for Daytona).