Text search lexer's handling of hyphens and negatives

(I sent a similar message before subscribing to the list but it hasn't
gone through yet, so sorry if you see a duplicate of this...)

We've been happily using pgsql to store user-generated documents for a
while now. We also wanted to be able to search the documents so we
tossed the document contents into a tsvector and did a pretty
straightforward contents @@ phraseto_tsquery('simple', 'the query').

Our users have a lot of things named like ABC-DEF-GHI so that sort of
hyphenated name appears in their documents fairly often.
to_tsvector('simple', 'ABC-DEF-GHI') @@ phraseto_tsquery('simple',
'ABC-DEF-GHI') works without issue.

Sometimes, these hyphenated names have numbers in them like
UVW-789-XYZ. Still no problem with to_tsvector/phraseto_tsquery.

Sometimes, users can only remember the last bit of the name. So they'd
like to find the document with ABC-DEF-GHI in it by searching for
'DEF-GHI'. Since to_tsvector('simple', 'ABC-DEF-GHI') is
'abc-def-ghi':1 'abc':2 'def':3 'ghi':4
we search for to_tsquery('simple', 'def <-> ghi') instead of using
phraseto_tsquery. This works, but you can probably see where this is
going.

to_tsvector('simple', 'UVW-789-XYZ') is
'uvw':1 '-789':2 'xyz':3
because -789 is a negative integer. If we turn the query '789-XYZ'
into the tsquery as before, we get to_tsquery('simple', '789 <-> xyz')
which doesn't match it.

Are we missing something here? Is there either a way to
1. generate tsvectors without this special (negative) integer behavior or
2. generate tsqueries in a more intelligent way?