I work for a moving company in the summer and I've been able to put on a few pounds this summer, even though I'm working hard in the heat all day. Working in the summer two years ago I lost almost 50 lbs, but I have worked harder to at least maintain my weight this summer.
The biggest mistake I made two years ago was that I wasn't getting enough protein.
This year I eat lots of eggs and turkey bacon with a cup of oatmeal most mornings for breakfast.
I have one or two 8 oz burgers each day, or another high protein sandwich or wrap. I don't usually eat so many carbs, especially from wheat, but it is the only way to eat enough and fast enough if you don't get long breaks. Accept that you may not be able to maintain an ideal diet if you are working outside doing hard labour.
I also have two 60g protein shakes during the day.I go for fruit flavours, because when it's hot out you may not want to be having any sort of chocolate or vanilla flavours.
I may also have a granola bar or something else with my shakes, especially the one in the afternoon if I'm going to the gym after work.
I haven't been as restrictive with carbs at dinner time, but usually it's my postworkout meal. Even if I don't have dinner until about an hour before I go to bed I will still have 1 or 2 scoops of a casein shake before I go to sleep.
I also haven't been eating as clean this summer, but I am relieved that I was able to maintain my weight and even put on a few pounds, while working hard all day. I am looking forward to school starting up again so I can eat healthier than I am right now.