" Meanwhile, the park’s RV residents would receive nothing. Where would they go?"  

"ORS 90.645
 If a manufactured dwelling park, or a portion of the park that includes the space for a manufactured dwelling, is to be closed and the land or leasehold converted to a use other than as a manufactured dwelling park, and the closure is not required by the exercise of eminent domain or by order of federal, state or local agencies, the landlord may terminate a month-to-month or fixed term rental agreement for a manufactured dwelling park space: 
 By giving the tenant not less than 365 days notice in writing before the date designated in the notice for termination; and 
 By paying a tenant, for each space for which a rental agreement is terminated, one of the following amounts:
(A)
 $5,000 if the manufactured dwelling is a single-wide dwelling;
(B)
 $7,000 if the manufactured dwelling is a double-wide dwelling; or
(C)
 $9,000 if the manufactured dwelling is a triple-wide or larger dwelling."