If you want loads of room, look into a 3P tent. You can find some that are not much more that 6 lbs. Maybe even lighter. Marmot Aeros 3 comes to mind. And older model that you can sometimes find on sale on eBay and at other places.

I took a 3P tent on my last tour in MT and Canada. The two of us apprecdiated the extra room, which we had lots of since my partner is a petite 5'. Although I carried the entire thing myself, if travel with someone you can always split the load.