With ratio restrictions it's harder to run the type of program that you want (in my experience). I run a Montessori preschool program along with my daycare. Truth is that I LOVE it! I love being home and I love still teaching. The reality of it is that it's very hard to mix ages in a way that makes it possible for me to run my program the way I'd like to. I aim for 2-4 years olds. Last year I filled my spots and it was great! Downside is that this year I had to fill in the spaces that were left open when the kids went off to full day kindergarten. (I'm in Ontario). Now it's my understanding that the kids start school later in Alberta which would work in your favour! I mentioned mixing ages. Let's just say that teaching a nice peaceful lesson is next to impossible when chasing after a baby who is (albeit age appropriately exploring) pulling everything off of the shelves and eating them! LOL. I've done the mixed groups before and find that I really need to separate the areas of the classroom.
Bottom line is that it's doable with a bit of work. Lots of parents will like that you teach the kids. I always include the preschool aspect of what I do in my advertising so that parents who DO want just a play environment for their kids need not apply! Best wishes!