Not certain what a visor has to do with neck pain, personally I like mine to keep the sun a little more out of my eyes, offer that touch of shade that helps the glasses work better, maybe make sure the fit on the helmet is correct as the visors typically don't sit lower than the rim of the helmet and shouldn't require extra strain. More upright will be the way to go, not certain how much a rental shop will do that, too much and cables start having to be replaced. But I would assume a rental shop is also going to be using gravel/adventure bikes more than pure road bikes these days, they're designed to be more comfortable than a race bike and closer to a touring bike but still fairly quick and light. And you also don't want to go too upright, or it puts more pressure on the butt which can slow you down even more.