Topband: 160M/80M Vertical - Using a capacity hat below a trap

[rich kennedy via Topband]

I’m finalizing design for my 160M/80M shortened wire tree-mounted
vertical.  An Unadilla 80M trap will be
placed approx. 65’ feet above the feedpoint; above the trap is another 20 feet
with a small cap hat.  An autotuner
handles the Z matching for the anticipated 500 watts on both bands.
 
QUESTION: Can one install a capacitive hat directly below
the 80M trap to help shorten the length of the 80M section?  For example, shortening the 80M radiator to
60’ (from 65’) and making up ‘the difference’ with a capacity hat?  Any downside?
 
NOTE: Please omit suggestions about using a larger hat on
160M (sloping wires, etc.) – I know that it is much more desirable, but that is
just not feasible here at K3VAT.
 
Thanks, 73, Rich, K3VAT