If going full time to school again isn’t financially possible, I think you still have hope. Even though the IDSA advices getting a degree, we IDers are not architects, we don’t have permits to be IDers. However, I would advice at least taking a few classes part time. I know my university offered materials and human factors classes to anyone, and you will need this knowledge if you pursue ID.
Moreover, you will need to bulk up your portfolio in a product way. I would recommend getting some ID books. Such as Product Design and Development for general development, Industrial Design: Materials and Manufacturing by Jim Lesko for a little manufacturing background and Creating Breakthrough Products by Cagan and Vogel for some research concepts. After doing a little reading, assign yourself a project in your free time. Perhaps by this point though, you won’t like ID anymore.
If you still like ID, I would recommend finding an area you think you would enjoy. If it is watches, do some watch projects. Make physical models as well, not just computer. Although, get ahold of a designer at a prospective company and find out what they use and learn that.
Lastly, be prepared to fight like hell. There are probably lots of people who will be intimidated to hire a GDer as an IDer. But, if you have the talent, and can demonstrate you are ready for the transition, it is possible.