While I'm not an expert on this, I am fairly certain that a 22 degree angle is not ok.
Are you sure you really need the WDH? You've got a full size truck and a single-axle travel trailer with a GVWR of ~4000lbs.
Check if the trailer manufacturer recommends against a WDH too. Some of these single-axle trailers are not built heavy enough to withstand the forces of a WDH on the tongue.
Rather than a spring bar style WDH, you might consider a sliding-bar style with built in sway control like the Equal-I-Zer E2. These appear to be capable of a wider range of hold-up bracket locations.
Another possibility is the Andersen No Sway WDH, which uses horizontal chains instead of spring bars. Its design also appears to be such that it would work with the brackets installed a bit too close.