Yep been there myself, did 15 years as a Carpenter from framing houses in the suburbs, Highrises in DT Chi-town to building up displays in stores (pure gravy) In my 20's it was not to bad putting in a long, hard day then hitting the gym. But by mid-30's you already feel like an old man, had to get out!! Still in construction but hung up the tools 7 years ago, now I just kind of observe the the work going on, LOL.
Hardest part about manual labor and training especially for BB is it does make it hard to keep on quality size, cause the work is so repetitive and slightly aerobic. So especially trying to diet for shows you never know how much to eat. Plus all that spent energy that you should have for the gym is lost on the job site
I would say drink as much water as you can and eat as much you can all day, pack some protein bars with you so you can have them between breaks.
Thats probally why I am making the best gains of my life at this age because, I got away from the manual labor.
And trab I hope you wear your respirator ALL the time when dealing with the dust and sprays, lung disease is very real in the trades.