What's the best way to expand my business?

I've been a sitter on Rover for over a year now and this has pretty much turned into a full time job. At this point I can either continue operating at capacity or find a way to expand to take on more dogs....but I don't feel I have the infrastructure in place to handle more dogs. I have a 4/2 house about 2,000 sq.ft on 1 1/2 acre of land. The grass is starting to get worn down and I need to make house repairs, but I am always full and having to CONSISTENTLY turn away new clients. I had 11 dogs here this last week which was at 180% my normal capacity, but many were repeat clients and they couldn't find anyone else to watch their dogs because of concerns about the breed (pit bull mixes). I've also been requested to offer training services by some clients to help with their behavior. The only two solutions I have so far are to add a second story to my house or buy my neighbors house next door. Any creative thoughts from the creative thinkers out there?