I would support an age maximum of 65

I can't agree there. I've seen 70+ yos that are more capable than 50+ year olds in handling complex tasks like policy negotiations and whatnot. So I think we should instead have an ability-based standard where you're removed if you're unfit for office, regardless of age. Perhaps that means psych evaluations by an independent org and presented to the judicial branch or some legislative committee for evaluation (I forget who has authority there).