Weird that endurance bikes are just now able to handle 35mm tires. Unless you were just referring to those specific models. My Felt VR85 an Endurance bike from 2016 can handle (unofficially) 40mm. And I’ve been running 35mm tires on them.

About the width of your tires and the rim. For my road bike, which has 27mm wide rims, I went with the 25mm Pro One TLE instead of the GP5000s (which I love), because everyone says that the Pro Ones are the easiest to install, and like you mentioned, I too wanted the aero. What a pain. One tire can’t seat properly.
Ordered the 28mm, hoping for better fit.