I wouldn't shorten the chain unless you're running a max length chain (barely clears the pulleys in the small-small) or you go to a smaller small chainring or cog.
If you're really adamant about no front derailleur then I'd just a N-Gear Jumpstop on the inside of the ring. To the outside… don't know, but a big effort in the small-small (like a 34x11 for example) will pull the chain toward the outside of the bike. If you're leaning to the right, if you hit a little bump or something, the chain will come off. I watched it happen in front of me in a Tues Night race a few weeks ago, some jokers insist on doing the race on single speeds (another one showed up on a fixed gear and was told to pull out of the race).
If you can stand the idea of a front derailleur I'd either use something like the downhill racers use or get an older/worn front derailleur and cut the tail off. You want just the U shape thing at the front. While you're at it you can drill holes in it and stuff. Or you can fabricate something with a light band and some piece of welded aluminum (?) to hang a U shape cage over the chain. Remove all the cables and stuff, you just want the U shaped guide so your chain doesn't want to pop off.
Aluminum chainring bolts are just more sensitive to over-tightening. If you hear creaking then it's probably done. If you buy Ti ones you would have more reliability and you could use them on your bike normally. Just use anti-seize and loosen them regularly so they don't freeze.
Is it possible to use downtube shifters? Or are there parts where you need to be able to go while shifting?
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