Can a novation work on a park that still has tenant-owned homes on half the lots

The novation only moves the land and the lot lease stack, full stop. The tenant-owned homes sit on their own titles and those don't transfer just because you stepped into the seller's seat on the ground lease. What bit me was assuming the lot lease assignments were clean when three of them had addenda that referenced the seller by name in the rent escalation clause, not just the generic "landlord" language, so I had to go back and get wet signatures from those tenants to cure it, which took six weeks and almost blew my closing window.

The part I have never seen work cleanly is assuming the lot lease assignments transfer without tenant consent just because the novation documents are silent on it. What actually happens is you close, then three or four tenants refuse to sign amended leases, and you are collecting rent on a handshake while title to the land sits in your name with zero enforceable paper underneath it.

The home titles are a separate DMV or HCD chain entirely depending on what state the park is in, so you are right that those do not move with the novation. But the lot leases themselves can have assignment restrictions baked in from whenever the original park owner wrote them, and in a 40-lot park that old nobody has looked at those clauses in a decade.

Pull every lot lease before you structure anything and count how many require written tenant consent to assign.

What does the seller's original purchase agreement say about the lot leases, are they assigned individually or swept in as a block under one master clause?

That distinction matters a lot because a block sweep in some states has been enough for a court to say you accepted duty of care over the homes even without touching a single HUD title. I'd get a title company that specifically does MHP work to run a lot-by-lot lien search on those 22 before you close, not after.