Lampost:
You have a great question and like many people are saying to get an answer to the equation you have to eliminate variables. Lumens per square foot is what your looking for and you answered many of your own questions i.e. strain variations and plant numbers. I think you hit the nail on the head by suggesting to veg your plants for a longer period. Colorado has a plant limit not a space limit and bigger plants equal more dry weight. I wouldn't necessarily increase your watts (unless you can subsequently control your temperature.) Regardless of where you want to be it all starts with where you are, and good genetics are the best place to start. SUBCOOL seeds offer some of the best genes around and they are available here in Colorado. PM me and we can talk some more. I hope this helps.