I've done exactly what you are thinking of doing. I was a cm for over 10 years. I started when it was under social services and left just as Ofsted were introducing more and more paperwork for cm's. My own children were old enough not to need me at home after school (14 and 17) and my dh, whilst supportive of me being a cmer, is not into children like I am and he used to make sure he came home after the children had gone. Not fair on him as it is his home too.
Pay wise I could probably earn more as a childminder if I had a full quota of children, but due to space in the car and preferring to have a smaller number of children I do earn more as a nanny. I also get sick pay and holiday pay. I no longer have to faff around keeping receipts and filling in tax returns.
My hours are longer when you take into account the commute time, but my house is now my own again - no more posters, stairgates, travel cots, buggies, car seats, small toys etc. If you take into account clearing up after the children have gone and doing paperwork, then I probably work less hours.
There are jobs out there with the hours you are thinking of. I've recently worked 7.30-6 and currently do 7.30-5.30 - I choose to work 3 days a week and when I was looking there were 3,4 and 5 day jobs with those sorts of hours. I live in a commuter area and there are also quite a few jobs that are 7-7 which is to long for me.
I always look for employers who have a similar childcare ethos to me and who are happy for me to manage the day as I would like to, though I'm always mindful that I am now an employee and would follow the parents wishes more than I maybe would have done as a cmer, this is easier though as you only have one set of children and their parents to consider.