RadioBanter - finally putting copper to the torch for 20, can I make it work for 30 too?

All,

I'm finally putting together a vertical antenna that I hope will work
on 20 meters.

Soil is sandstone with occasional bits of granite, impossible to drill
into, it has to be
chiseled out with a hand pickaxe. I won't begin to tell you the agony
involved in
chipping out a 2 1/2 foot cubic hole into this stuff, but I managed to
do it.

But in any case forget about soil conductivity, and forget about ground
rods! There
is a single ground rod courtesy of the electrical company... probably
not at good
depth for RF but it is the only game in town.

Construction:

The ground half of the antenna starts with 5 foot of 1 inch diameter
iron pipe,
sunk halfway into hole filled with concrete. 2 1/2 half feet of iron
pipe are exposed
above the dirt. This is connected to 10 foot of 3/4 inch copper pipe.

At the 12 foot level I am mounting 4 radials, 8 foot 1 1/2 inches in
length, of 1/2 inch
diameter copper pipe. I am also mounting 4 copper guy wires, same
length, that are
intended to also work as additional radials.

The radiative half of the antenna starts with 10 foot of 3/4 copper
pipe, topped with
a 9 foot carbon fiber fishing pole. A thin copper wire of about 6 foot
3 inches in length
will be run up the fishing pole, for a total length of 16 foot 3
inches. I will be mounting
rope guy wires on the botttom of the radiative half.

The ground half and radiative half are connected together with a PVC
coupler, and make
contact with each other inside the coupler via a thick styrofoam
spacer.

Question:

This antenna is designed to hopefully work on 20 meters. If I run a
wire of 14 feet 4 1/2 inches up the fishing pole instead of the 6 foot
3 inches, and if I use guy wires of 12 foot 2 1/4 inches, leaving the
radial lengths unchanged: will I get a vertical that I can work on
both 30 and 20 meters?

Thanks in advance,

The Eternal Squire