4x8 is also preferable for the lumber dimensions aspect.I would get a 4x8 and even with 2 600's your going to need at least a 6in fan to keep them cool.
5x10 is to big, you would be having a ton of wasted space like a foot all the way around.... personally if you can get by without using a tent your much better off.
I ran tents for awhile and they are more trouble, headaches, and expenses getting dialed in then they where worth.... at least that is how I feel now about them.
I like them because im able to run 2 4x4s on a flip, a mom tent, and a small clone tent all within a 11x9 room. Never had a problem with light leaks or hermies.I ran tents for awhile and they are more trouble, headaches, and expenses getting dialed in then they where worth.... at least that is how I feel now about them.