The big downside of your current approach is its inefficiency with large search result sets, as you have to pull down the entire result set from the database each time, even though you only intend to display one page of results.
In order to only pull down the objects you actually need from the database, you have to use pagination on a QuerySet, not a list. If you do this, Django actually slices the QuerySet before the query is executed, so the SQL query will use OFFSET and LIMIT to only get the records you will actually display. But you can't do this unless you can cram your search into a single query somehow.
Given that all three of your models have title and body fields, why not use model inheritance? Just have all three models inherit from a common ancestor that has title and body, and perform the search as a single query on the ancestor model.
