I hadn't thought of the trailer scenario, that really puts things into perspective. Or what if you plan to use aero bars? And then not all handlebars have the same reach, so you need to figure that in too. As well as the goal of maximizing comfort in all 3 different hand positions, hoods, drops, and tops. More compromises there.

Seems like such a simple subject at first, but it quickly becomes quite complicated if you worry about it too much.