[Mee-n-Mac]

I'm asking for some thoughts on a secondary anchor for the "Mee-n-Mac". It's primary purpose would be to tie the stern down so it doesn't swing with the wind when in close quarters with other boats (who've done likewise). Think fair weather rafting more so than foul weather e-gear. I don't need anything as robust as the primary anchor but then again having a back-up isn't such a bad idea (and would surely be my choice if on the ocean, just not sure where I'd store the thing). What have you used for an auxiliary anchor that worked ? ... that didn't work ?? What would you recommend for a 24 ft, 5000 lb boat ???