I understand where you are coming from, V, but I would see the request to do a professional development day for your colleagues as an honor. Infuse it with humor and you will get them laughing, even if they never come close to what you are doing. Model what you do with your kids with them.
I was in the very same position as you a few years ago. Some of the teachers hated me, and eventually they left; retired, etc. I was seen as the evil empire brought in form another district and before I knew it, there were new, young teachers all around me and they all were on the same page as me. It only took a few years and a superintendent who kept pushing for change.
I wouldn't change anything with your math; keep doing what you are doing. I only had 21-25 kids when I taught fifth grade and even less when I looped with 6-7th.
I am now dealing with horrible teachers in my new job, when I have to meet with the schools where my clients attend. What's even worse is the way some of their parents are treated, just because they are poor and have all kinds of challenges.
It never stops.