The simple way is to drive to a truck stop and dolly the tongue jack down on a scale. Back when I was part of a race team, we had a lever-type multiplier that we used along with a simple bathroom scale to measure up to 1,000 pounds per wheel. It was set up so the scale indicated 1/4 of the actual weight bearing down on the device.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!