Welcome to Healing Well.
You say you have been on a liquid diet and now you are considering a outdoors type construction job in the heat with heavy work involved???
Did I get that right?
Is this the type of job you would choose for you if you were actively looking and not a job offered by a friend?
My concern would be your nutritional health is not good at this time.
You could go on a high protien, high calorie liguid diet. But you would really have to work at making sure you stick to it before you venture out in the hot weather for 8-9 hours a day.
I hope this has helped some.