As for Ben’s reference to Richard Strauss the correctly spelled googling is here:
http://www.google.dk/search?client=safa ... OOOOn7vZoP
(May sound grumpy, but Americans not familiar with German should at least be aware that invariably are wrong in their sequencing of i and e, if they spell German words by ear. The reason is simple, as English and German have reverse phonetic interpretations of these two letters. Danish and German are similar on this matter, so one often sees American references to the never existing Danish composer Neilsen. Carl Nielsen is the right name).
As for the OP’s request there are two sad matters:
The lack of a large pool of double brass quintet repertory.
The reason why there is no large pool for double brass quintet.
As for the latter:
4 trumpets are fine.
2 horns are fine (very much better than one)
2 trombones are one or two short.
2 tubas in a 10 piece brass ensemble not dedicated to low brasses is nothing less than overkill.
One obvious remedy would be letting one of the tubists play cimbasso thereby making up for the missing bass trombone.
Grumpy as this may sound grumpiness is not my agenda, especially not towards a project sponsored by the Hollie Ghost (I am not speaking behind her back!). Inspired by your posting I looked through some of my material and found some light music and some grave music, which might be adaptable especially if Bill and you split between bass and contrabass tubas. Also some music for the 4 or 6 lowest brasses, if the trumpets need a rest. The music is in the index found via the upper of my signature links. Composers would be Grieg, Marais, and Woods plus a Negro Spiritual and some Danish folk dances in a quite virtuoso setting for minimum 2 trumpets, trombone, euphonium, and contrabass tuba, but with a number of optional parts. The horns may do the stuff for 2 euphs.
Klaus