As a rule you will always want to remove your rear sway bar at a trailhead, unless you always have it off.

The front sway bar is also disconnected if you know that you will be running a tough trail, say 3+ out of 5. I have driven with the front (and rear) off for a couple thousand miles just fine - but it is not recommended due to the body roll. You just don't drive it like a car when you are disconnected.

Unless you are towing, the rear sway bar can be left off indefinately. Just remember you will have more body roll and it isn't a Miata.