Partner steel makes great anodized aluminum dutch ovens with griddle lid that are trapezoid shaped. They are welded together, not cast like most other aluminum dutch ovens.
The Rome Super Cooker, the big rectangular one with the griddle lid that fits perfectly on a partner stove and makes a great DO for meals for 8 to 10 peeps, has almost a cult following, but haven't been made for a long time and Rome has no plans to fix the problems they had to produce some more.
If Partner Steel made a hard anodized aluminum dutch oven he same design they have now:
but made it a similar dimension as the Rome Super Cooker:
would you buy it? Just for assumptions, lets say $200 or less, as their most expensive 14" DO is less than $150 currently.
I inquired to Partner Steel today on this topic and they aren't interested in adding a DO to their line up at this time, but an inquiry by some unknown yahoo like me probably doesn't mean much. A thread with a bunch of stoke may change their mind. It seams to be a simple matter of just making their existing DO longer instead of square shaped. Since they are welded, its not a casting problem, but a matter of programming a machine or building a jig depending on how they cut out the pieces that they then weld together.
They already make a "lasagna" pan on special order that is nearly the same size as the old Rome Super Cooker but it doesn't have a lid. If they added a griddle lid to their lasagna pan, there you have it.