Another option that you should consider: co-operate with a good hosting vendor and direct your web design customers to that, when they need. Offering a good hosting service will require you spend most of your time on net. You will need to answer your customers' requests asap, day and night. It's much different than offering web design service. Why don't you focus on web design service, your strength?
I have some friends doing that way, and even more: they don't offer graphic design. Just do coding. Customers can get graphic done some where else. At first, it looks they are losing customers. In fact, they focus on what they know perfectly, the niche, and they are always busy enough with customers.