Do you live in a free state? If you go out of state is it only to free states? That would mean no stop overs in non-free states if flying. If then, a SBR. They're fast. And while fake barrels to get short barrels to 16" isa thing, a SBR doesn't mess with a 16" anything, barrel, or fake extension.
Here's my RFRO, I was the manufacturer and all the parts are off the shelf. It started with a Ruger Charger Takedown with the goal being the smallest, lightest to pack rifle that I could build. Then I realized that I built a (to my way of thinking) perfect RFRO, It evolved and as I realized "this would be better" I removed what was on it and added the new part(s). It weighs 4# 8ozs pictured below if memory serves. I have handguns that weigh more than it does. Due to the TacSol barrel it's a tack driver. Thanx to ATF the buffer tube and stock I had on it came off, and an arm brace I had on another pistol came off of it and went onto this. That dropped the weight 8ozs to what it is today. That change also made the handgun it was on smaller, lighter, faster, and just as accurate because now I cheek it and I'll also wind up with faster times in RFPO. As an arm braced handgun it wasn't acceptable in SC, but as a handgun it is. So now I drive once and I shoot both handgun and rifle .
OK, the downside to a SBR. If it goes across state lines ATF needs to be notified ahead of time. I don't so that's no big deal for me. If you fly to a match and for some reason the plane sets down in a police state, you're screwed if anyone detects it. If it's illegal there it's illegal there, pure and simple. Again, I don't do that but if you do it could be a major issue. Myself, if I desired to leave Maine to compete (I have no desire) I would just leave the SBR home and just take the handgun and even that would have issues in states that aren't free since the smallest mag for it is a 33 rounder.
edit: I forgot a downside. ATF collects a $200 tax so that the builder, in the case of the above rifle, that would be me, out of jail for 20 years. You must have the tax stamp in hand before beginning any work on it.