If you were already maxed out in your weights, adding more equipment would push you over and maybe then you should reconsider the trailer. But if your weights are as you stated, you have plenty of allowable tolerance, especially for added safety equipment that's going to help manage pulling that weight safer! You could try hooking up your trailer without any equipment and see how the van is affected. You may not need airbags or WDH depending on how well you load all your weight (cargo, batteries, fuel etc.) Sway you may not know you need it until you need it and that could be a bad day. My experience was I definitely noticed I needed sway control when I got up to highway speeds. When I crested any small hill and started to descend at all, the trailer wanted to try passing me, and would start sway left and right. They say having proper tongue weight would minimize sway, but I had a tongue heavy pop up trailer with the extra cargo box on the front over the tongue and it still swayed.
Next I noticed the need for WDH. The front end of the van was definitely lighter due to the leverage of the tongue weight behind the rear axle. The front end felt like it wanted to float and wonder a little and I would have less traction, especially since I only have FWD. When I saw that the front end could be brought back down with WDH but the rear end still sagged, I got the airbags. The springs in the rear were pretty tired already with out the trailer, so the airbags have been nice to have all the time.
My current WDH setup has integrated sway control, mostly due to simpler set up. Also opted for straight bar trunnion style (see here:https://www.etrailer.com/Weight-Dist...2-00-0600.html
) because it would allow for better ground clearance than most round bar styles. Most trailers that we're pulling in our weight class ride lower to the ground as it is so any WDH that installs lower than the tongue is getting pretty close to the ground!
Oh, and as an after thought...some hitch receivers are rated different. Some may not be rated for use with WHD and only allow tongue weights of 350lbs. where as others are rated for 500lbs. with use of WHD. Your mechanic might be taking that into consideration. You can still get sway control only easily enough, they're light and simple, even if you don't get WDH.