I used the black plastic from a old oil bottle to make spacers and fill the gaps.
By using plastic if you dump the bike in the future the indicators will pull free more easily without any further damage and will go back in place just as easily.
Seconding that idea.
I've done a very similar thing another bike and found that it worked very well. I had to use a little bathroom silicon sealant to help keep it all in place (and keep any water out as part of the loom for the headlight ran right next to, not sure if it was needed but as I'd got it all apart didn't seem to be a bad idea) but it held and didn't move about.
The more you think the less the better.
Notable bikes: SV650S (Sold), Kawasaki ER5 (Being repaired), 01 Blade (Sold), Another SV650S (Sold), 05 GSXR1000 (Sold), Suzuki GSF400Z (Sold), Yamaha FZR400RR Streetfighter (Sold), Kawasaki GPZ500S (Sold), Yamaha XJ600 Divvie (Crashed), 04 Kawasaki ZX10R (Written off at Snetterton), GSX750X (Sold), 04 ZX6R (Sold), 02 ZX6R (Sold), 94 FZR600R (Sold), 91 NC30 (Sold and missed), 87 GSXR750 (Sold and really missed), RD125LC (Crashed, rebuilt then sold).