Matt,
Look for any truckstop that says SCALE. Most have them.
You don't say where you are, but the Detroiter on I-75 at West Road (Exit 32) is easy to get to. There is another in Romulus just west of DTW. Or find a scrap yard, they weight everything in and out.
Remember to set the conditions before you weigh. Is fuel and water full and black empty? How much of the normal traveling stuff do you have on board? An acquaintance was having tire problems. He had weight the trailer when he got it. The he put on 200 pounds of water and his wife loaded 300 in canned goods.
Matt