Is it correct to list several past perfect verbs in a row, and use only one "had" to apply to all?
e.g.
"I had fished, camped, and cooked out before I threw in the towel for the weekend." I assume "had" applies to all three verbs (had fished, had camped, and had cooked).
This happens all the time in English. Where does the influence of a word end? Look at this:
I am extremely wet and tired.
Is this person extremely tired? To make it clear, you could repeat extremely, but what if the person is not extremely tired. How do you make it clear then?
In your example, I judge it's fine to let the influence of had wash over the other verbs, but, in truth, English doesn't handle this very well. You have to make your own judgement.
Here's more on verb tense (only tangentially related to your question).