Sorry, I didn't spot this thread earlier!
I don't have my rig all hitched up so I can't do measurements today, but my recollection with my 2019 2108DS is that the drop was something like 17.25". From the fitment guide you'd think you'd need the "raised brackets" (also known as "low profile brackets"). But you don't.
I called Anderson about this and came to two conclusions. First, the regular brackets are part of the kit and you pay for them either way. Anderson's suggestion was to try them and see if you really bottom out as you tow over expected road conditions. The other conclusion was from the observation that my rig is setup at the lowest height setting. These Winnebago 21xx trailers have three height settings, each of which lifts it about 1.5". That's true of my 2019 model year, and may be true of following and prior years as well. So if you have a 21xx trailer and are thinking "what the heck, I think mine must be around 20 inches off the ground," you are probably right because yours is at the upper height. So the net conclusion was that if I did bottom out due to road conditions (i.e., a driveway transition), I'd more likely raise the trailer rather than go out and buy the low profile brackets.
I could go measure the frame. It's either 5" or 6", I can't recall, but this is the kit I ordered:
Andersen 3380 No-Sway' Weight Distribution Hitch 8" Drop / Rise, 2-5/16 Ball, 3", 4", 5", 6" Universal Frame Brackets. It all worked out of the box. My Land Cruiser hitch is very high so I needed the 8" drop.
Here's my setup. The picture is more of a mockup, though, as I had just connected the wire and hadn't pulled it back yet. It really was as easy to install as you think. And you do need a 150 lb torque wrench. Note the urethane springs really do compress! Also, it may not be clear from the instructions, but the bolt adjustments at the end of the chains really only needs to be done once. When you lift with the jack it all loosens up, and pulling the pin drops the plate to the ground (dangling on the chains). Reverse the procedure to put it back on. No pry bars or any of that. When I setup camp I do take the hitch assembly out of my receiver, but that's about the only extra work.
Finally, make sure you get all the grease out of the coupler! On my first outing I was disappointed in the sway (though we did have 40mph wind gusts that day -- lucky me). but I found there was leftover grease from the previous owner. A bunch of spraying with WD40 and wiping out with rags cured that and made a HUGE difference. Of course it needs to lock onto the ball for the anti-sway to work.