Tips for a long haul?

We will be attending a show that is about 6 1/2 hours away...What are some tips? This is our first long haul, we are going down the night before so it's not to hectic. Do we leave them tied? And every say 2 hours get them out and walk them and get them some water? We are taking our own water with us...I would like to see all of your tips! Also, anything I can do in case they end up getting stiff legged or look sunken in?

No farther than you are going,  just go.  The problem is having them too full or too full of water that their guts bounce with every bump.  1/2 feed and maybe 1/2  a bucket of water wait  hour or so and get on the trailer.  And when you unload, don't do a full feeding,  or watering.  Some hay, a little rest,  a bit of grain and you will be fine.