I am having trouble finding a skylight to meet the following
specifications:
1. Fit existing (external dimension) curb of ~35" x 50"

2. Work on (existing) minimal pitched curb (roof is flat, curb is
pitched at ~15-20degrees)

3. Allow (infrequent) access to roof (our roof is 30+ feet high and it
is a PITA to use a ladder so I would like to be able to access it
via the skylight).

4. Ideally, it would also be nice to be able to open it
more regularly (even if partially) for ventillation but this is
not an absolute

5. Be compatible and flashable with rubber roof (current curb is
flashed in EPDM on top of our flat rubber roof)

6. Ideally, insulated glass, though I would accept
polycarbonate/acrylic if no options. Could even be a "hatch" type
model as long as it was transparent.

Velux sells only one residential "egress" model (GPL) and it comes in
only a couple of sizes none of which are close to what I need. They also
seem to sell a polycarbonate commercial model (CVA) but it too comes
in only limited sizes.

Other vendors like Fakro sell similar models but again only in a few
sizes.

So, any suggestions on vendors that might have a wider range of sizes
and models?

Are there any reasonably priced and reliable custom shops who
specialize in this?
I saw a company called Newenglandskylights.com (which is actualy only
a few miles from me) but they seem to be truly high end custom,
creating historical-type looks out of copper.

I have also seen several companies advertising "hatches" but they all
seem to be aluminum or steel while I need something transparent to let
light in the space (plus they all seem to look pretty ugly).

Any ideas?