How about "try to get the rule changed before you commit everything to buy something you can't have".
Again, this is the most friendly HoA I've ever heard of. They gave him an entire year of owning the thing before they started pinging him for a rule he was violating. They put the rule to a vote to let them see if there was enough support to overturn it. They've purposely given him an indefinite amount of time to get the rule changed rather than closing the issue when the vote failed. They circulated two official fliers around the community to try to help the kid get the support he needs so the rule can be overturned; against an unofficial flyer pleading other residents to keep the rules the same. If all of that still isn't enough to get the support of the neighborhood to overturn the rule, then in no way should he get to keep the truck as he has been, no.
The contract his parents signed forfeiting their ability to have their home appear in a way outside of what the neighborhood collectively agrees is proper is a pretty damn valid reason, I'd say.
It definitely is. It's too bad that that's not actually a thing, legally speaking.