Welcome to the fora, wonderingj. There has been a lot of good advice on the thread, so let me add just a few things that haven't been mentioned.
I have been rejected for administrative positions by every law school in my area (though I made it to finalist in several of the interviews) and I don't want to move due to my elderly parents. I have had no success obtaining interviews for non-law school administrative jobs in universities.
You need to know that higher education is a highly competitive industry and the jobs for which you are applying receive applications from all around the country. It takes time and energy to get a job in higher ed. Zharkov's Law states that you should expect that the number of applications you send should exceed the average number of applications received for the jobs for which you apply; therefore, if there are 100 applicants for the student-affairs jobs (a not unreasonable number even for a law school) then you should plan to apply for 100 jobs. If you are unable or unwilling to move, your chances of obtaining a job grow much weaker.
1. I think that I am interested in student affairs but I am not sure since I have never tried it. I think I can arrange to do a couple of days of job shadowing in a local institution but can someone suggest any other ways I could test out my interest? I would like to volunteer with students but would have to do it on the weekend or at night. I hesitate to leave my profession unless I can really test out my interest but I am stumped as how to test this out in a meaningful way while working full time.
Are you an alum of any of these universities? If so, call up the alumni association and tell them you'd like to volunteer in some way; they will help connect you with the right people. If not, call up your alma mater and offer your services for free. Then take a few days off and go to that location to do your volunteering and shadowing. You should also do informational interviewing while you are there: explain that you are not interested in a job at Alma Mater because of the distance, but you'd appreciate advice on breaking in.
2. Should I get a masters in higher education administration to make this career transition?
An HEA degree is more useful for dealing with undergraduate populations than law school students, most of whom are nonresidential and adult (legally anyway). You might consider it if you want to work with undergraduates. But I believe firmly that no one should pursue a degree that isn't interesting in itself, including the JD. A degree guarantees nothing. Don't do it if you don't want to.
There are lots of jobs in higher ed. Read books and talk to people to determine which jobs interest you the most. Good luck.
Good luck.