Topband: 160/80 Meter Vertical Performance Over Poor Soil Conductivity

[ronbon at att.net]

Here goes my first attempt to pose a question on the topband reflector.

I am considering a possible move to Southwest Missouri, specifically the
Branson area. The books say that soil conductivity in that area is 8 mS/m.
For the following reasons, I believe the conductivity is probably not that 
good. There appears to be only about 6 inches of soil on top of rock.  So I
suspect that the books are not accurate.  It is not possible to drive
ground rods.  The power company lays ground rods horizontally in the bottom
of their trenches when supplying power to homes.  I'm told that you can dig
holes for towers but you must remove lots of rocks in the process.  Below
6 inches there is soil and rock mixed followed by solid rock. (Separate
from RF ground issues, lightning protection is also a challenge.)

I have studied ON4UN's Low Band DXing book, the ARRL Antenna Handbook, and 
other sources including past discussions on this reflector going back years.
I believe I understand the near field vs. far field issues as related to
vertical antennas, and understand that poor soil conductivity will cuase
suckout at the lower radiation angles.

So, here are my questions.  If I install a full-size 1/4 wave 80 meter 
vertical and also use it for a 160 meter inverted-L, with 120 radials each 40 
meters long to solve the near field ground loss problem, will this antenna be
a useful DX antenna on both of these bands with very poor soil or will it
be nothing more than an "air-cooled dummy load" as one person suggested. 

The antenna will be on a ridge 200 feet above Lake Taneycomo
on nearly flat ground for at least 1000 feet in all directions, much longer
to the east and south.  No other higher ridges or mountains loom in the 
distance.  A 75 foot tower for the higher bands would be about 200 feet
from the vertical/inverted-L.

(I don't consider high horizontal antennas as an option for me.)

Will a psuedo Brewster angle of 15 degrees make DXing difficult on 160/80?

Can I likely enjoy low-band DXing from Branson, or should I stay in the
good soil of Northern Illinois?

73, Ron W9MAF