i doubt it will take the project gutenberg c.e.o.
"a few weeks" to get back to you on this, bob...

but in case it does, you're welcome to munch on
my response here, coming from someone who has
absolutely no official status with project gutenberg.

***

project gutenberg doesn't like hand-crafted files...

of _any_ type.

because it's usually too difficult to maintain them.
(for instance, to correct any typos that're reported.)

that's a general stance.  nothing personal.  sorry.

***

more to the specific point, however, the problems
that you've noticed have been seen by many people,
and there's been growing realization that the .epubs
need to be improved.  so recently an effort has been
started to put into place a workflow to achieve that...

for p.g., this will involve an improved .epub converter,
plus a contemplated shift to "restructured text" (r.s.t.)
as a "master" format that can generate a "better" .epub.

(where "better" often means "dumbed down to the pale
imitation that still challenges many e-book-machines".
i'm not familiar with all of the sony-reader models, but
it would seem that yours is one of those primitive ones.)

meanwhile, over at distributed proofreaders...

d.p. has likewise started related initiatives, three of 'em.
one is aimed at installing r.s.t. within the d.p. workflow.
another wants to make slight changes to the "traditional"
workflow to make it more amenable to better .epub files.
and the third is looking at using .html files as the "base"
from which an .epub can be converted.  as you'd imagine,
there could be quite a bit of overlap in these approaches,
but the efforts are still being headed by different people.

so, to boil things down...

in terms of your handcrafted .epub files, the response is
likely to be "thanks, but no thanks, thank you very much."

however, the wisdom you have gained is very important,
and might be very useful over at distributed proofreaders.
(it won't be useful here at p.g. proper, because marcello,
the guy who's in charge here, already knows _everything_.)

so i'd suggest that you go over to d.p. and sign up so you
can read their forums, and explore the 3 different threads
where the separate approaches are being discussed (a bit).

after you've done that, it will probably be apparent to you
where you should offer the expertise that you have gained.

a word of advice on the people at distributed proofreaders:
they are like abused animals, so if you approach them with
any kind of self-confidence, they will lurch out and bite you,
but if you approach with an extremely deferential attitude,
they will be more than happy to welcome you very warmly...

http://www.pgdp.net
http://www.pgdp.net/phpBB2/viewtopic.php?t=45852
http://www.pgdp.net/phpBB2/viewtopic.php?t=45853
http://www.pgdp.net/phpBB2/viewtopic.php?t=45856
http://www.pgdp.net/phpBB2/viewtopic.php?t=45866
http://www.pgdp.net/phpBB2/viewtopic.php?t=45548
http://www.pgdp.net/phpBB2/viewtopic.php?t=45562

-bowerbird