I am in about the same boat, i am making good money now but would like to do it more automotive/ mechanical engineering based, going back to school soon for mechanical engineering.
What I am doing right now is easy plus its only 4 10-hour shifts usually only working 1 weekend day and on call 1 week a month, which is all OT. Starting pay is $19 an hour and OT is usually 10-30 a month minimum. PM me for more info but given your background you could easily handle this job, and we have a few guys on our team that just work hear so they can finish their degrees while making making good money. Its a 24 hour operation so you could work pretty much any hours around you school schedule. Also during the slow season i just sit and do homework for almost the whole 10 hour shifts on nights and weekends because no one is in the office and there is no work.