Use of <q> within <rs>

Is there any particular reason why <q> is not permitted within <rs>?

I am attempting to mark-up archaeological findspots that occasionally 
quote from another text, e.g.:

    <rs type="findspot">said to have been found <q>5 km from centre
    [of <placeName>Bath</placeName>], near a quarry near a villa</q></rs>

and

    <rs type="findspot">in excavation, re-used in a fourth-century
    <q>chalet</q></rs>

However, <rs> does not permit such usage of <q> (or <quote> for that 
matter), notwithstanding its being defined as "a _general purpose_ name 
or referring string".

Is there some other sanctioned method of accomplishing my goal of 
distinguishing the quoted text from the passages within which they appear?

Thank you.