I took WC for a test drive. It works well, though I just wove a leash through the mesh to attach it to the cart as I don’t have enough clips on hand. WC was only a tiny bit apprehensive when we went out of places he has been on a leash, to the side of the road, even though no cars went by. But he was mostly relaxed and curious, and didn’t want to get out, once we got back in the yard. HB didn’t seem to notice we left, and when we came back, he checked things out and retreated to one of the perches in the orchard. He in seemed to think WC was a weirdo hanging out in the cart. So this might help reduce WC being so competitive if he gets some one on one time with me... I am going to take it slow though. I really don’t want to create more problems than I solve!
If people have enough people in the household to manage two cats on leashes, assuming the cats don’t get obbessed with going out, there probably isn’t a lot of advantage to using a cat stroller... but in my situation the stroller may be a nice enrichment for WC. He likes going places! Even the vet was surprised how relaxed he was...