I used to work construction as well and I know where you're coming from. It's hard damn work. Working out after work is damn near impossible unless you have a lot of motivation already. Fortunately, I did, but my workouts weren't that good.
I found my best bet was to workout early in the mornings before I went to work. This meant I had to get up earlier but I didn't miss any workouts and I was always fired up after some coffee.
First, invest in some tupper ware and try to cook your meals the night before. I'd then pick a program that allows for 3 days of lifting per week, probably Chad Waterbury's. This should give you 2 days during the work week and one on the weekend. Do cardio when you can, but don't over emphasize it because you're getting a lot of cardio in your job already.