I think what you want is a 50°F or 40°F summer quilt. Under 13 ounces but $230 at Enlightened Equipment:

https://enlightenedequipment.com/revelation-stock/

Assuming that is in the shell shock range I think your best bet is to buy the quilt from Costco and either sew your self a foot box or find a local sewer to do it for you.

There are a lot of links out there about how to do this. Here is one:

http://www.trek-lite.com/index.php?threa...-blankets.2454/

one issue with doing this is you end up with a fairly short quilt. That may work for you as a liner though it would depend on your height.