Hey Nicewing, A lot of the bar end mirrors that you can buy, you can actually remove that little piece that opens up inside the end of the handlebar. This leaves basically a Clamp on 7/8" mirror which you can either attach on the inside of your grip (towards the frame) or if you move your grips in about 3/8 - 1/2" you should be able to clamp it on the end of the bar which will still leave the end open to attach your bar end signals.....
I'm not sure if i'm explaining this correctly or if it will work that way with the bar end signals you have. But I hope this may help, may just take some playing around with the fitment of everything but you should still be able to get it to work. Let me know if I can help.
- Eric