StargazeCyclist It sounds like you aren't considering a new bike, but if you were, you might consider an e-bike. It could raise your average speed and also allow you to easily pull a trailer. And if you can pull a trailer you can fashion some sort of major isolation for your telescope.
Even without e-assist, a lightweight trailer with a large underinflated excercise ball, or multiple underinflated air mattresses may provide the cushioning the telescope needs, although without e-assist the going would be even slower.