Got back home for Xmas and finally got to fix the tail - you guys were dead right, epoxy is at least as light as cyno .
No need to thin the epoxy with thinners, heating with a hair dryer is more than enough to get it to wick right through and wet nicely. Penetration through the skin was no issue, in fact you have to be real careful not to put too much on as you need to be very swift to wipe it back off before it's absorbed....this almost caught me as it's not like my heavier slope wings! That's a heavy iron milling plate on top of a wood board/foam/PTFE/FF tail/PTFE/foam/cd case sandwich...rough and ready
In the end I couldn't be bothered to get out the vac bag kit as I expect to replace the tail soon anyhow, but in the end that made no noticable difference to either the finish or strength - see for yourself. I'll be going old school on all but the highest stress repairs now as TBH bagging's a b**ch for those little jobs!
Right back to decorating the house and the insanity/stress of the Xmas run up....too much family, too little time