We had our entire driveway (over 250 feet long and 30 feet wide) resurfaced about 4 years ago. I had them slope the drive way from side-to-side because it had a natural slope down hill from the road, right into my garage. When it rained, water flooded my garage.
They ended up sloping the drive way when they raised the entire existing asphalt under it. the one side was raised with 6 inches of asphalt and the other side was raised by 4 inches of asphalt, plus they extended the width another foot to make a firm edge.
When I parked the Montana on the new surface, it was badly leaning left-right. I ended up getting 2 - 2x12x8 foot boards. I left one 8 feet long and cut the other at 7 feet and stacked them, using the front end for a gentler ramp.
The end result was, the trailer sat almost level, left-to-right. Adding some lumber under the jacks on the low side to raise them a bit so they would not stroke out was all it took.
If yours is sloped front to back, and one end will be too low for the lacks to properly level, then add lumber under the tires to raise the entire trailer, giving more clearance for the jacks. Leave the lumber there, and when you return from your trips, you always park the tires in the exact same spot.
Here's an exagerated drawing of what I'm talking about
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Of course, use treated lumber. It cost more, but it last forever!