Re: Long distance towing.
I tow my 24' pontoon boat on a dual axle trailer 350 miles one way to Canada for vacation ( holiday ) three times a year. Before the spring trip, hubs are repacked with fresh grease, bearings adjusted , tires inspected ( looked at closely ) and air pressure set a 5 lbs under max settings. ( ie, 90 psi max gets 85 psi )
I have TWO spares and carry a floor jack and a fair amount of tools.
I have this set I purchase at Sears
plus plus carry larger wrenches and larger sockets plus a 1/2" breaker bar.
At every stop, I lightly touch each trailer tire and hub to make sure they're not too hot. I do a quick walk around to make sure everything on the trailer is in place ( hold down straps still attached & any items in the boat still secured ). My first stops are close together ( 20 miles and then at 50 miles )and later they are checked at gas stops. I keep looking in my mirrors to make sure the tires look OK as I'm driving too.
This seems to work well for me as in over 10,000 miles of trailering, I've had one flat tire and one broken spring perch from a construction pothole in the road.
Jeff