[Lowfer] HiFER antenna?

[KD7JYK DM09]

Anyone modified a 20m Hustler Resonator with a longer whip to drop it down 
to 13.5x MHz?

It the factory stinger long enough for this?

How much length needs to be added?

I see a lot of replacement stingers for various antennas for sale, varying 
lengths and diameters, thought of using a Hustler for reception while 
mobile, wondering if anyone has done this for RX or TX.

Kurt