Not only is there an issue with the space on your body, but tat guns can only do a line so small..
Most of the small characters will end up as colored blobs, and I would be amazed if any reputable tat artists didn't advise you to tone it down.
I would recommend scaling it back to maybe 6 characters at most.
Either that, or do a Perez sytle multi-head shot of everyone. Boring, but you could get everyone in that way.