Is independent research a good long term goal for a bachelor's degree holder with experience and interest?
It seems you have two options to weigh against each other:


Do research independently, viewing it more as a hobby than as your profession, or
become a professional researcher, which would require getting the appropriate formal education.


If you want to make research the most important aspect of your life, then option 2 would be the way to go. However, from your current biography, it seems that this may require more effort and changes to your life than you may be willing to invest. Getting a PhD is a definite requirement along this path.

If you go for option 1, it will still be possible to make research an important aspect of your life. It will be more difficult though to maintain sufficient investment of time in view of work and family commitments to keep things running.

Personally, I think that being a hobby researcher can be viable and satisfying in research fields where you don't need expensive equipment. While the examples I know mostly do something like locally focussed historical research or botanical/zoological research in their environment, it seems that mathematical or theoretical engineering topics will also be feasible for this. If you want to go that way, the internet certainly provides much more advice on being a hobby researcher than I can hope to give here. A link to start with may be this question on cstheory.stackexchange.com.