When we got our 4500 Chevy, it made the trailer nose high also. I cut off the receiver part of the trailer ~1.5" allowing the coupler tube to go up in the receiver hitch that much farther. Measured the depth of the receiver to make sure it would not bottom out and still have another 2" or so before it hits. Went as high as possible which was flush with the bottom of the gussets welded on the receiver. I did call the trailer manufacture and they were fine with it.

Good luck and enjoy the truck!!

Out in our part of the country we frequently "Block" the axles to gain a couple inches of ground clearance so we can travel down Forest Service and BLM dirt roads. Not something most trailers need for traveling to and from the fairgrounds, But us back country riders find it very helpful.

Most competent trailer repairs can do the job, It involves taken off the axles and placing blocks on the trailer and rewelding everything back in place.  Around here it is usually a $300 per axle job. Or $600 for your trailer. And most usually life the trailer around 3"

On my trailers it has taken my rear step up height from 17" to 20".  This has not been a big deal for the horses since I usually let my horses turn around and walk out.  It can be a little bit of concern if you have  managers and a tighter inside space where you need the horses to back out.  My horses get a little nervous with that big of a step off when they are backing out.

If I am asking them to back out, I take a little extra care to try and position the wheels in a low spot that helps to lower the rear step height.