I agree papajoe, blade size is a very important factor (smaller, less lift), along with skirt strand count (sparse = less lift) and line diameter (thicker = more bow).
Line may not seem like a difference but I found myself in the ocean deep sea fishing in an average tidal current. I was in 100 feet of water vertically jigging w/14# mono. My reel holds 100 yards of 14# line. I dropped down and was almost spooled. That night, I switched out to a stronger and thinner line dia braid and went back the next day. I dropped down and a 1/4 of my spool had line.
I don't expect people to believe that, just sharing a real experience.
I also think that getting a 3/8 oz SB down to 15' is attainable. I do think you'll have a better feel for an SB with 1/2 oz or more. The lighter SB in that depth may not be felt by most anglers or at least they won't think they are rolling the bottom. My original post was merely pointing out that it is attainable it just might not be desirable. I was just sticking with the topic.
Have a good day. I'll be done here.