You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
Done a few in the past on older bikes using either a tensioner on the derailure hanger or a bb mounted stinger style.
Current bike wont take a bb mounted one due to clearance so need a decent hanger mounted one. Also does anyone make a non narrow wide chainring to fit Sram cranks? That way I can use a half link chain.
Don't use a half link chain...they stretch something terrible!
Best rear SS tensioners are (imo) the double jockey wheel ones like Paul's and Rohloff. I've picked up both cheap in eBay in the past.
There is a similar 2 jockey wheel Shimano Alfine one too, but needs a bit of care with the chain line (not adjustable like the others)
Its not that half link wear/stretch badly its just there is no take up of the slack. So you set it just right and the normal wear is soon evident with nothing you can do about it.
What bb shell? If its press fit get a eccentric converter?
old rear mech was my fave tensioner.
xtr if you are bling.
Its a BSA bb shell. No spacers on the bb either. I tried a bb mounted tensioner but it made the shell too wide for the cranks.
+ 1 to not liking half links, happy to be able to lose mine with a change of gearing.
Philcentric if you want to keep BB tensioning and fancy splashing out - does the same job as an adjustable half-link.
Or something a little more "special"

a squirt of water heavier than an Alfine, full adjustability for chainline.
Philcentric if you want to keep BB tensioning and fancy splashing out
If there is one that would work with my Sram Dub cranks I'll give it a try.
Ive tried a few over the years and have had Alfines on my singlespeeds for quite some time, race bike and commuter. As ajantom says the two jockey wheels ones are the only ones which seem to work. You can adjust the chain line on an Alfine though, well ,on one direction, the thread for the hanger is huge and you just put washers behind it. Obviously not as adjustable as an old mech though