Just went on a steel search myself.
Specialized makes a steel frame Sequoia with discs, more of a town bicycle.
Trek makes the 520, but good luck seeing one on the showroom floor. I think frame only. Geometry should be close to your Domane.
I ended up ordering a Bianchi Volpe gravel bike. I already have a older Campione and figured the geometry couldn't be that far off. I converted the Volpe to sidewalk hopper.
Bianchi also has the Orso, a gravel bike with discs (in a weird military green/orange color). They also make a couple other steel frame bicycles.
If not for the Volpe, I would have ordered a Surly Crosscheck.
You might check GVH bikes, they are still listing some frames on the website.
At the upper end of your budget, you are awfully close to custom frame range (Carl Strong I think is around $2200, but that means getting in the queue and waiting). That would be frame and group. If going that route, I would save up and get some really nice wheels!
Building up a frame shouldn't hold you back. Do what you can; source out the heavy stuff that you don't feel confident about to the LBS.
I also keep an eyeball out on the local craigslist for vintage frames.
Good luck!
