...My HP LP3065s measure 3x 27.2W x 9.5 x 23.2H inches...
... does the 14.5" cylinder detach from the base or is it welded on?...
The central mounting pole attaches to the base via a grub screw so can be swapped out for another with a suitable O.D.
The maximum monitor width according to Ergotron for the triple with long crossbar extension, setup how Ergotron designed it, is 24.5" each or 73.5" total. This is for a monitor with a panel thickness of 4" though if it is thicker then the available width is less.
You need to gain approximately an extra 11 inches of crossbar width (total), from tip to tip, to fit the 3x 30" monitors you listed.
You need to gain approximately an extra 9 inches of crossbar width (total), from tip to tip, to fit the 2x 28" and 1x30" monitors you listed.
You should be able to get this extra length using the long crossbar kit and Scooby's modification to the DS100.
I don't know if I'd be happy mounting all that weight on such long levers. As Scooby says I would also recommend clamping the base to your desk to prevent it tipping forward. Currently I've got a strip of aluminum flat bar under the front of the base to rotate the monitors up a bit and move the C.O.G. back a little.