this is won't be a painless thing to say but may get them off your back more quickly...
"I need to get a qualification from college that will put me in a better position to pioneer in the longer term. To do this I need to pay for college which will require I work full time and as a result I will have to come off pioneering temporarily. I know we are in the last days of the last days but I have prayed long and hard about this and now confident that Jah has given me the answer.
I will really miss pioneering so this will be hard to do, but as soon as I complete college I will be in a more stable position. I also found the following publications really helpful: cite a few WT from the 90's that suggest that some qualifications may be required.
I really hope that you support me in this decision because I want to be as successful as I can at college so I get get back to pioneering as soon as I can - I really don't want to have to repeat a year or anything."
Is there an older, well respected pioneer that you can talk to who will conceed that you may benefit from improving your financial position now to help you pioneer in the longer term? Anyone you can get to see your point of view and then quote them and say you've made your mind up?
Good luck - you are doing the right thing. I gave up pioneering, got a job, eventually went to college and now living in great house in a great area and doing the things I want to do - it is worth it.
MMXIV
PS. just before you finish college, move out of home and never go back to pioneering.