Newbie ... your quilting idea is so awesome, it should be patented. In three years someone is going to bring this to Market, mark my words.
I have done FMQ for some time and have not had a problem quilting as big as 72" square. But I am not comfortable doing a pattern - I do lots of meandering (puzzle pieces). But I have quilted two double/queen size quilts in two pieces. The toughest part is when the two pieces are sewn together and I have to do the last row of quilting in the center. It can be done. It can be beautiful.