Hi Tom
If you're heading out to a dark site you should be able to get a pleasing result on NGC 6188. I imaged it last year with my Canon 60Da through the C11 @F7 form north west Sydney (orange/red zone.)
You might not have to go as long as you think re exposure. I found 4 minutes was prefect for my camera in respect to the LP I have here. 10 minutes will probably be too long for the DSLR. Take some short subs, 4 to 6 sec just for the star cores then combine these with the longer subs during processing. This helps retain the star colours. Make sure your subs are dithered, take accurate darks and flats and you'll get a nice result.
Here's a link to my pic for reference
NGC6188
All the best
Rod