hi chris
this is aimed more for stacked images (as the have better signal to noise ratios). but the idea is the same for stretching. you won't be able to do as many iterations as its a single exposure and not stacked.
http://myastroimages.com/Astro_Imagi...toShop_Curves/
I'd recommend opening up the f stop a bit and/or upping the iso.
cheers