You can have questionable credit and buy a car,banks will trust you on that,reason being,if they repo your car,your not loosing you job and being able to pay back the balance of the note,have your truck repoed,now your out of work,and they know they are going to probably never see the balance of that note.
If and big if,you have lots of equity in your house,if you own a house,taking That truck on a house note,you could put that truck on 10 years and have a very small payment.When your weeks are good you can make bigger payments,and when they are bad,at least that small paYment won't hurt that much.