I purchased those heatsinks in bulk from rapid before they offered the kit or frame, but they are the same sinks. Marine grade wire should work great, just make sure you’re getting rated for high enough voltage. A lot of them will use 60v rated conductor and that’s not good for our application.
I purchased hlg-185-1050 for my cree’s. Should run them at about 40 Watts with dimmer circuit open, and will be plenty for my application. I was targeting a little more efficient setup, and they should run about 60% efficient there. But I’ll also be running in a much smaller area than you, so the need for a little more power wouldn’t exist as much as in your tent. It’s easier to justify more power because you can raise the fixture and create a larger footprint. The only real downside to the bigger driver is the efficiency losses you start to see above the 1400ma range. The bridgelux vero’s Start to become more efficient, and you could’ve saved $12 a cob going with them. But it won’t really make a difference if you don’t intend on running at 100% all the time. Running them at about 80% on dimmer will give you same efficiency of 1400ma driver.