I agree...use a bottle jack. There may already be one in your tow vehicle, with the spare tire...and use something under it to raise it to the proper height and distribute the weight so the jack won't sink into the ground/asphalt... you may also already carry leveling blocks, which can be used for this purpose. It may also help to run the unaffected wheel (on the same side), up onto some leveling blocks before jacking up the affected wheel/axle. Always place the jack under the axle as close to the wheel as possible, when jacking it up...not the trailer frame. Your jack doesn't need to be that big, I believe you'll be lifting less than 1000 pounds, (trailer only weighs about 4400 lbs, and some of that is on the hitch). Once the axle is jacked up, as a precaution it probably doesn't hurt to drop the stabilizer jacks as well. Oh, and make sure to loosen the lug nuts on the flat tire/wheel, before you jack it up. Good luck.