One positive piece of info about your project. I did the exact same project of raising a 33 foot travel trailer I used to have in 1982.
Most people don't know that the spindels welded on the ends of the axels have positive camber in them to make your tires set at the correct angle to lessen wear on your tires. And also reduce the drag on the towing angle. So when you flip the axels over you now have negative camber on your tires and wheels. You can actually see this if you go to one of the big alignment shops where you can get your trailer on the rack. Then they can show you when they measure the camber.
The proper way to do the raising of your trailer, is to go to one of the businesses that sell axles the correct size for your trailer and buy a new set of saddles. I see your pretty handy with welding so this will be a piece of cake. Now position the new saddles 180 degrees around your axel from the original ones. Tack them on and double check the position. Once your satisfied with the positioning weld them on.
Now disassemble the u-bolts from your spring packs. Roll your axle over 180 degrees so the original side is up. This fixes the camber problem. I assume the original spring position was under the axels. So now position the springs on top of your axel on your new saddles. And reassemble with your original u-bolts.
Now you still have your the additional height with the proper camber so you won't be eating up your tires.
I worked in the field for 45 years as a heavy equipment mechanic off of my own F-700 field truck. With 400 amp Lincoln diesel welder and all of the associated tools from 3 inches down. I did the explained procedure to my trailer in a mining camp named Stibnite Idaho at 6700 feet elevation. While my family was living in the trailer. I jacked it up and blocked it up on blocks and crawled under it and did all of the work on the side of a mountain.