I'm still working it all out, but can give you a few ideas...I actually posted here a little while ago saying I was feeling a bit discouraged about my ability to balance homeschooling with everything else, but that's past!
Can you keep doing mostly what you've been doing? The main difficult issue is paying for childcare past the point where your child would be going to school. You can look into having him stay with another homeschooling family or with friends/family. Everyone has a different set of challenges and resources, so it's about getting creative to find what works.
I once saw a good piece of advice on a single parents homeschooling list - work for yourself, unschool (ie follow your kid's interests not curriculum), and create strategic alliances with other homeschoolers esp single ones.
I used to employ a nanny, and ask my parent's for childcare help sometimes...but neither of those are really suiting me right now. Getting my dd out to events and activities where she could meet other kids isn't that easy (not driving is a biggie). But I recently found this interesting school, which is a free school that is okay with me being there with her. So I'm thinking that I will bring her there, and do some of my own work there while helping them out. The women that work there are all single moms, and today we were talking about how they aren't homeschooling - they are schoolhoming -- in a way they homeschool their own and other people's kids at school! I can totally see why this works for single parents, because it means you are still with your child, but not isolated.
So I would look into finding your homeschool community and trying to create some kind of co-op arrangement. Most cities have yahoo groups for the local homeschool community, and they list lots of activities and resources that come up. Our city has 4 drop-ins and stuff like homeschool guides and scouts.
BTW, there is also a yahoo group for working and homeschooling, as well as many other types of homeschool lists. And on here there's a homeschooling discussion section. There are tons on online resources, many free. Some single parents like things like time4learning.com ($20/mo) because the curriculum is already there but the child chooses the activities, and it can be a backbone that you can add to, with trips and hands-on stuff.