I would like horuses opinion on
this
Shuttles, I'd defer to TtTOtW. They're his speciality/passion.
However since I'm here, several questions / points.
1. I take it you're not using an ET/Booster? It's your choice whether you do or not, but I would consider using them for the reason that you can get further and swap the engines on the shuttle for smaller, more efficient ones and let the booster do the heavy lifting.
2. The batteries you have fitted in the nose and payload bay are surplus to requirements. You can get rid of them.
3. The fuel tanks in the 'tail', overlap them somehow with the main body fuel tanks and the engines will draw from them without having to do fuel transfer in flight.
Aside from that, it's not a bad punt at a shuttle dude.