Cylinder Gap Mods for 15 KV

Richard, a quick question on the archive site cylindrical gap design.

I'll be running a 15 KV supply at 90 ma. initially in my new coil,
using one of the commercial caps that we recently ordered.  I'd like
to try out the cylinder gap design initially, but noticed that the
number of electrodes and gap spacing is designed for a 6-8 KV system.
I was wondering if any design modifications, particularly gap size, could
be done (short of building two units) which would allow 15 KV operation
at 1.4 KVA.

Also, I was planning on using the surplus end from my 1/8" wall, 6" diameter
acrylic secondary form to build the gaps. I have a 9" length left over
from my 27" secondary form.  Aside from the lack of UV protection, do you
see any problems with this.

Thanks once again for the help.  The secondary will be wound after
Thanksgiving dinner tomorrow (hopefully).  The pile of parts in the workroom
is growing steadily.  My wife smelled the ozone in the basement from the
transformer tests the other night, and gave me that "oh no, not again" look!