I fully agree on wanting a two person tent. The morning when you have to travel and there is a constant rain, you will be happy that you can pack up all your gear in your panniers while you and your gear are still within the tent. Then once it is all packed, and it is still raining outside, that is when you pack up your tent.

There is a store near my home that has some giant shopping bags that are a very heavy duty plastic. I often use the plastic from their shopping bags as a ground sheet instead of buying one that is made for the tent. Some people have used Tyvek. The ground sheet is to protect the tent, if the ground is soft grass, I do not bother to unfold the ground sheet and just put the tent up.

There was a comment about ground sheet in vestibule. I have no complaints about the ground as long as it is in a grassy area. But my last tour, one campsite (the most costly one of the whole trip) was a tiny little site with no grass, mostly mud. There was a used newspaper in a recycle bin that I used to keep my stuff out of the mud, photo taken from inside the tent looking towards vestibule.