First off, good question. I have direct experience with your situation, although I was a little younger when I was in the same quandary, so I can give some insight to what I encountered, and decided. I assume your not thinking you can sell your engineering services without a PE stamp. You could offer CAD service, but to make money you better be good.
I was an electrician, I became and engineer, why? I thought I could use my experience in the field to do better designs. During engineering school, I realized very quickly, that being an engineer and being a designer are not one in the same. Once you finish school, you can go to work for an A/e or E/a firm, or strictly engineering firm, or Contractor. Design will be required, but now, hopefully anyway, you will have a better understanding of why you are making certain design decisions, i.e. theory behind the choices. CAD capability is not always required as an engineer, (I have never done CAD work) but it completely depends on who you are working for, and in large part dependent on the type of work they do. I work for a large engineering company, we have specific CAD people, some of them are Sr. Designers.
Other firms, such as A/e and E/a, the entry level engineers, will often do CAD work, typical of commercial and building type projects. It's not until you get to the upper-mid, and Sr. level that you design and someone else does CAD.
Because I do have designers on staff, this is what I can tell you about them. They are worth their weight in gold, especially if they can do CAD as well. Designers with no CAD capability are still useful, but you better be able to come in at a Top SR. level and immediately produce. Essentially do just about everything an engineer can do, but without the degree. That's tough to do without previous office experience.
The practicality is, that starting at nearly 50, if you have no prior school experience, you are going to be starting with 18yr olds, who may actually know more than yourself. If it's been some time that you've been away from school you may need to take some review courses at a JC. I had to do that even though I did do college straight out of High School, couldn't remember the basic algebra stuff, it's very humbling to say the least. Ended up getting an AA from a JC before going on to finish. You are going to need to feed yourself while your in school, but night classes are not always available because lab work is required. Engineering and day job? So say you can finish in 7-8 years. You have an engineering degree, with a lot of field experience, and no CAD. Entry level engineer pay will be around +/- $45K (that's a real ballpark and a lot of factors) not sure what you were looking for.
On the flip side you have good field knowledge (journeyman/master electrician) with bidding capability, or at least how to do estimates (worked for yourself). You take 9-months of CAD classes from ITT or something, to learn how to push the buttons, and learn the basics. Maybe even look into CM certificate/degree. Now you are worth something to a manager or large Contractor that has engineering/design in house. I'd say your pay probably goes up to $65K-$80K. If you are willing to travel; even more, and this took a year, maybe two.
IMHO, you would be better to go the CAD route and work toward CM. You will not make as much in the end, but it would probably take 10 yrs after you get your degree to make the same as you might get with your experience combined with CAD and CM in a much shorter time frame.
I guess this is also assuming you don't have a socialite wife to support you, but if that was the case, you'd probably be sipping Mai-Tai's on the beach, instead of pondering a career change.
