OK, so here is what i have currently.
as you can see there isn't much chain wrap at the moment, roughly half the cog. as the frame lengthens under compression the tensioner gets pulled up and i gain more wrap but not a huge amount.
Chain growth on the set-up is a fraction over one link so i'm having to run 2 links in all, if i take that extra link out I'm running the risk of twisting the frame / snapping the chain. I suppose i could try find a half link (Charlie, we spoke about this briefly at SSWC, I was the guy who the bike hut owner thought wanted just one side, left or right, of chain) but i don't see it making much difference.
What i'd like is to always have as much chain wrap as possible and the slack chain to be managed some other way. By the looks of it a tensioner in the style of a rear mech is the way forwards
Oh and for any bodge fans out there, the PCD (Podge's chain device) on the right is constructed from one old rear light bracket, an old DMR bb mounted jockey wheel and a beefy bolt. its basically to stop the chain flapping about, fitting it around the chainstay protector means its tight enough to stay in place but loose enough that if it does get knocked the chain brings it back into line.