Raising the trailer

I think 3 - 4 inches is a tall order. The problem is that if it has leaf springs the only way to lift it is with longer brackets. I don't think welding on 3- 4 inch longer brackets is going to be very strong.

A flipped axle will give you 5 - 6 inches of lift. Yes it's a bit of a lift and if you're not 6 feet plus you'll find it to be a big step. Most people who do an axle flip wind up getting a low stool of some kind to add under the last step.

i would go to a shop that does lifted pickup trucks .
they may have a shackle kit or a blocking system to space your axle a couple of inches more .
with the available space between your axle and the trailer you also would be able to upgrade from a 14 inch wheel to a 15 inch wheel or a 16 inch wheel .
i did something similar to my boat trailer .
my komfort 21T already came outfitted from the factory for additional ground clearance to all of the other trailers that i considered .
komfort is made in oregon .
plenty of boondock camping opportunites in oregon .
their trailers weigh more than most due to an inch taller steel frame underneath.
they have shock absorbers , large holding tanks , spare mounted under the frame next to the axles , welded aluminum house framing , and so forth .
gravel roads chew up cheap trailers.........