My situation is slightly different, but maybe it will help.
Last year, I was a stay-at-home mom/substitute teacher, and served as secretary of our PTO. One evening in May, I was elected President. The next day, our principal hired me to work full-time in a para-professional position. One active PTO mom told me that it was a shame that I'd have to give up the presidency since I now worked at the school--it might look like a conflict of interest. I'll admit, this got my back up, and I told her that I had not seen any rule that said a school employee could not also hold a board position. Any PTO member in good standing could run for office. Nothing more was ever said, at least not to my face!
From the start, I was very conscious of the potential for an appearance of conflict of interest. I decided that if any business came up that directly involved the areas I worked in, I would not be the one to bring it up, and I would not vote on it. Things have worked out fine.
When discussion of things like staff appreciation come up, I just stick my fingers in my ears and go,"La-la-la-la-la-la-I cant' hear you!" They just work around me in those cases. Usually, I'll participate from both sides: as a PTO volunteer, I'll sign up to bring a dish for the Staff Birthday Brunch, and then as a staff member, I'll go eat the goodies that have been brought to us.
I know that your situation is different in that you don't know where these previously uninvolved teachers are coming from. But please, don't give up your committees and involvement. I have a feeling they'll need your knowledge and experience to run things successfully, and you'll probably have more influence that you think.