I was pretty intrigued by this craft! I gave it a go and I found this:
1. Stock lifter design is not great. It is way OP, maybe skipper instead of mainsail?
2. It was tending to flip pretty bad - I had to change the fins for some bigger, better ones
3. I added struts to hold shuttle more steady
Once I got into orbit things were pretty sweet! I havent tried docking yet, but I´m sure it would work. Actually you have enough fuel to fly to Mün and make decent orbit, maybe even dock to station. That would be a great addition to its capabilities, if it would be capable rotating crews between Mün and Kerbin orbits. I love the simplicity of the design and low part count, it will be no problem to use it as escape pod for space stations and such aplications. I will gladly integrate it into my fleet!
I look forward to more crafts from you!