I cannot help with T5-12 specific tips, since I've only ever played one once in a store. I use Elixir light gauge sets exclusively on my twelver's as I hate to change that many strings. I've been quite happy with them.
One thing that I do is swap the wound and the plain G string course. I mostly finger pick, so the up stroke of my index finger is shielded fully from the octave string in the normal configuration. You can hear it missing. I've done this for years with all of my twelve string guitars. 95% of the time it is not even necessary to widen the slot in the nut; I just switch the strings. Pay attention to which tuning key you are turning though, as the pattern isn't "normal" as you move from button to button.
Very pretty guitar, BTW. Big koa fan here.