Back when I was preload several guys had their own jobs (own business) but they just told mngmt they had a full time job. Just tell them you have to go to your full time job if they ask you to stay.
If you go preload (like 4am to 8:30-ish) and you have to go in the morning the drivers always appreciate it if you let us know you got to go. So we can watch for our stray boxes. Lots of guys just work PT for the benefits. Hey why not I had to have emergency surgery last year, was in the hospital for weeks, I paid $25. For insurance I pay $0 for.