I build my wall mount frame like I was building roofing rafters and attached them to to 12 ft ledger boards that were screwed into the wall studs. My top beam is steel uni-strut attached with angle iron corner braces screwed into the 2x4 frame. One of the disadvantages to doing this way is that you are married to the angle you cut your frame pieces at.
Other people have hinged their frames at the top to allow allow changing the angle or swinging the entire thing up against the ceiling to get it out of the way.
Also, I have to confess I ended up going back to a 10ft frame, after some home repair work, the frame was blocking access to a ruptured hot water tank, I still use the same frame layout, but I’m not using my maslow to cut full sheets and taking up the extra real estate and storage space in my garage was hard to justify. I cut without issue as long as I stay within a 4 ft x 6 ft envelope when cutting.