Welcome aboard Ladymoon, t-shirt quilts are such wonderful gifts but many of us don't enjoy making them. Good for you, I hope it turns out to be a wonderful experience -- but remember, if it isn't, not all quilts are t-shirt quilts
When I need a lightweight paper, and I will draw my quilting designs on it and quilt right through everything, is parchment paper from the dollar store, a 1x25' roll for a dollar!
If you still have phone books or a stack of old catalogs those work. So does cheap "newsprint" paper you can get at office supply places too.
I'm still waving from a safe personal space near Seattle -- but my mask is off!