There's a bit of debate as to whether or not cohumulone content is actually a significant contributor to a "harsh bitterness". There are still many unidentified compounds in hops, and we aren't totally sure how the balance of duties weighs out. Mitch Steele has some really good stuff about this...
The hop schedule looks pretty good for 3 gallons, although the flameout addition will result in some hop aroma. If you're really trying to avoid front-palate hoppiness, I'd recommend moving that up to 5 minutes or something. A few more IBU won't really be noticeable in that regard. IMO czech...
I'm sure this beer would be great in bottles! Nice looking recipe.
I'd recommend using an online priming sugar calculator to get it carbonated to around 2 volumes, but daskin might have a different carbonation level he would recommend.
What about consolidating your hop additions, instead of removing them? I've had good luck doing an ounce of each at 10 and flameout. I don't personally think it's too many hops but I agree with you about the carastan. Maybe even a half pound? You'll be getting plenty of mouthfeel and head...
I had a similar experience with wyeast 3711 French saison last spring. It was ridiculous. Fermentation and off-gassing was visible in the bubbler for like 9 or 10 days, in that consistent way you describe. It was a total beast. Took 1.060 down to .999 in that time.
Yeast does a lot of work after it reaches FG in the fermenter. It will clean up after itself, re-consuming acetaldehyde and DMS and a lot of the other nasties that contribute to off flavors in beer. A lot of the reason people leave it alone for a bit of extra time is to ensure that the beer is...
IMHO, mosaic renders on the sweeter side of the hop spectrum, so if it were me I would lean on the hops to cover some of the sweetness currently present in your malt bill. I think you'll still get plenty of malt flavor and character if you eliminate one of your crystal additions.
I have what is turning into my house APA base recipe with late and dry hop additions of AU Topaz which i've never tried before.
I also worked on an autumn ale recipe with Simcoe and Stella hops, high mash temp (156), some darker grains. Going for some toasted bread/biscuit and piney hop...
I feel like there's a really hip trend lately to use Nelson Sauvin and Citra as the primary hops in craft IPAs lately (lagunitas daytime comes to mind), and I think they both lend a real cat-pissy, white grape juice, oily element to beer. Not a fan of either in situations like that. Laughing dog...