Well, there is a way to have only one. You'll need to convert your rig to run on 50A service. I could be wrong, but I believe all you'd need to do is change the distro panel to a 2-leg one, run the second AC into the second leg, putting the rest of the trailer on the first leg, and then change the plug from a 30 to a 50, while also running the second leg from plug to distro panel.
With that, you'd be able to run the 50A protector since you're now wired for 50A just like any other 50A rig out there.
Mind you, this is all based on knowledge gained from reading posts on this forum, as I only have a 30A trailer, so I could be entirely off base, but from what I've gathered so far it doesn't sound implausible.
There's no use crying over spilled milk, unless it's on your keyboard.