I stopped by the LGS, and my friend there mentioned he was doing a 10.5 inch barrel with a permanently attached suppressor that measures 16 inches in overall length. This means you can buy one stamp for the suppressor but you don't have a SBR. Since you can cross state lines with a suppressor without issue, and you have a 16 inch upper, it becomes a low hassle way of having a compact length long gun.
Yankee Hill, for example makes one with a suppressor already permanently attached for about $1,000. Thoughts?