We replaced the carpeting in ours: got a remnant of Berber, used the old one as a pattern (it was also an opportunity to adjust the edges).
We wanted the carpeting to be easily removable (think checking for leaks) so we added another piece on top by the entrance to hide a strategic split which enables us to lift it up easily to check underneath.
I don't like the rough edges either, so we checked with a local carpet place to price having the carpeting bound. Quite unreasonable and indefensible for a trailer.
I searched for a more helpful carpet place and found it (Atiyeh Carpets here in Portland, an old firm with a great reputation). They showed me how to bind it myself and gave me the binding and thread.
It is actually very easy but a bit tedious. You need the binding tape, a needle, thick waxed thread, and a little hot glue gun. Not a professional job, but nobody notices the difference. The upside is that once you learn how to do it the prospect of replacing pieces, upholstering footstools, etc. is nothing to fear.