Hi Dave,
Why not just purchase a floating WF line. From the leader end of the line,
cut off all of the level and part of the taper. Attach braided mono loop to
end of line. Make a selection of 'lead heads' out of lead core line, ranging
from 1' to 12'. Then you can change 'lead heads' to match the depth you wish
to fish and still maintain the ability to mend line if needed. Pretty versatile.
If you attach the 'lead head' between the line and leader butt, rather than
between the butt and tippet of your leader, it will cast OK.