Before I essentially echo back what Stuart said, let me clarify something. I don't really recommend NAT over NDP proxying more than the other way around. I was merely stating that a hack is a hack is a hack. If you are forced to use a hack, then insisting on one over the other is bizarre unless one legitimately solves something the other doesn't. Personally, I would use NAT since it is more familiar to me.
What I am still befuddled by is your insistence on sticking with your incompetent VPS provider. I sympathize with your plight vis-a-vis a residential ISP. It is not uncommon to have monopolies/duopolies dominate a particular residential ISP market; so if they are incompetent, then you're SOL. VPS providers, however, are a dime a dozen. Why would you want to stick with a VPS provider that (un)knowingly does not adhere to RFCs? If they don't follow one RFC, then I wouldn't be surprised if they don't follow others. To me I don't view it much differently than insisting on renting a laptop with malfunctioning hardware or BIOS/UEFI and waving $200 at kernel developers to hack around the bugs. They might; but even if they do, is it not better to solve the problem at the root (i.e., rent a functioning laptop)? I pay $25/month for my VPS, and I think I could bring that down to $10 or $15 if I wanted. My VPS routes me a /48 IPv6 network via a link-local address and a /29 IPv4 network via a private address. I have two WireGuard interfaces: one for "normal" peers where they connect to this VPN server via WireGuard software (e.g., the Android app) and another for my server/router at home which subsequently gets routed a /56 IPv6 block and the whole /29 IPv4 block. Bam. Finito. No BGP, no problem. I get to stay within the cozy confines of good ole routing. No hacks or other shenanigans. It just works. Just in case people misinterpret above: I am _not_ recommending this over BGP if you have the money/resources for BGP. Obviously you want the shortest routes possible and avoid any overhead associated with a VPN.
