Is this kind of simplification allowed?
Great question. I believe it is. Compare:
(a) I went for a long run and swim.
(b) I ate a spicy taco and enchilada.
(c) I met a British man and woman.
l believe that each sentence admits of two interpretations. In neither interpretation is there any ellipsis. To illustrate:
(a1) I went for [a [[long run] and [swim]]].
(a2) I went for [a [long [run and swim]]].
In interpretation (a1), the complement of the determiner is the coordinate NP structure "long run" and "swim." The run was long and the swim was of unmentioned length. In interpretation (a2), the complement of the determiner is the coordinate NP structure "run and swim," which as a whole is modified by the adjective "long."
I try to avoid using the technical term DP (Determiner Phrase) in ESL discussions, but here I find it unavoidable. In the example (a), the DP is "a long run and swim." The two NPs (Noun Phrases) are "run" and "swim." They're coordinated, and the coordinate structure they form is itself a phrase. (I'm describing a syntax tree in words.)
The difference between the two interpretations is that in (a1) the AP (Adjective Phrase) "long" is an adjunct (i.e., a modifier) of the NP "run" alone, whereas in (a2) it is an adjunct (modifier) of the higher NP comprising the coordinated NPs "run" and "swim." I'm sorry if this is confusing. I suppose it's a convoluted way of saying "Yes."