I use exactly what Ted suggested. They were on the boat. Also use em to tie fenders so it's not around a stanchion base. I don't sail much DDW, so I don't rig a preventer as often as I probably should. (If less than 15 or so, I'll fly the asym - so no DDW anyway)
The base of the shrounds/stays (chainplate) are pretty strong - after all, they're holding the rig up. They're also bolted into the bulkheads rather than just washers below like on a stanchion. But they're not as convenient as using the genoa track slide - it's more outboard and thus gives a better angle.
You can also run one all the way to the bow - it's a better angle still. I've used my asym tack line for one before when it was too sporty to fly the kite - it was already there and on a block out at the pointy end.