The E2 hitches are usually chosen by tongue weight - buy the model rated higher than the tongue weight of your trailer. The number of washers (max 7) used to angle the head control how much weight is being distributed once the bar alignment has been set up.
My E2 600/6000 was set up by the dealer for an A122 A-frame (3150 max, 400lb (approx.) tongue weight). There was some trial-and-error difficulty in getting it right because the hitch on a minivan is close to the ground to begin with. But the dealer got it set up (with 3 washers), and I loved it. The minivan drove like normal, even when towing.
Went to T21TBHW high wall A-frame a year ago with the same tow Hyundai Entourage minivan tow vehicle. Tongue weight was higher, and aerodynamic loading quite a bit higher. Trailer was about an inch higher due to 14" instead of 13" tires. Did not adjust the height because hitch and tongue jack clear minivan tail gate opening in current configuration. Did add 2 washers to compensate for the extra trailer and tongue weight, which restored minivan ride back to where I wanted.
just my experiences
2019 Flagstaff T21TBHW A-frame
prev 2014 Rockwood A122 A-frame
2008 Hyundai Entourage minivan with E2 600/6000 WDH
camping Colorado and adjacent states one weekend at a time