The axle carrier appears to only be bolted to the bracket that is welded to the frame. It should be fairly easy to have a fabrication shop make a 'lift kit' for your axles from some appropriately sized square and flat stock.
There are a couple of different threads here on JOF where owners have done this. A quick search should turn them up.
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2018 Nissan Titan Midnight Ed.