Moondog, the Shanghai consulate told me that they will do up to two sets of extension pages provided the passport is in good condition. I checked a few others and they would not go beyond two extensions. Anyway, that should take a while to use up, especially if you use the pencil method to guide stamping and ask them not to stamp a new page.

I have seen first hand some people remove the adhesive full-page visas without a mark, I believe they were Brazil and Vietnam. I don't recommend that but I guess it could be an emergency option.

When a visa is applied upon landing right in front of me, I ask them to use the special endorsement pages which otherwise go unused. Many, but not all, do. If my passport is getting full I place two yellow post-its on each blank page and write "DO NOT STAMP- full page visa only" making them find a place on some other page. They get the message.

in the end, despite all my best efforts, my passports have not gone to their end of their 10 year expiration before I have had to apply for a new one. And then I do travel with two passports if the old one has a visa that I don't wish to re-apply for. Never had any extra scrutiny for that, even from US CBP when I applied for a Global Entry.

Don't see what else can be done.