[doc holliday]

1 and 3 are the best options. You have a skill which you can be paid well doing but the more time off you take, the harder it will be to find work in the field. You might be able to make money doing some of the other things you've listed but I highly doubt you'll be able to do as well financially as you would being an engineer. 6 months on 6 months off sounds really good to me and I would heavily lean towards that option. Plus once you get older and have the travel bug out of your system (and trust me you will), you'll still have your career to fall back on.