I use a Hi-Lift jack like seen on jeeps. https://hi-lift.com/
It has an attachment that allows you to connect it to the outside of the wheel with two hooks, one through each cutout in the steel wheel. It's called the Lift-Mate accessory. https://hi-lift.com/accessories/lift-mate/
That allows me to lift the wheel and place a jack stand under the axle between the two U-bolts easily. No need to use concrete blocks or lumber to jack the trailer. Nice and easy to do a wheel bearing repack. I actually put all four axle points up on jacks to keep the wheels off the ground during winter when it's not being used so that the wheels don't crease in one spot (I store my trailer in a fully enclosed RV garage with cement pad. It takes me maybe all of 15 minutes to put all four jack stands underneath.
This is also how I change a flat tire on the trailer. I lift the bad tire, throw a jack stand under it, release the jack, take off the bad tire.
The whole Hi-Lift system fits in the bed box in my truck. But they also make a locking rack that might be able to bolt to a trailer bumper.