Greetings,
While many are going very deep and attempting to create this "loophole", the reality is you applied the tap rules to the outside conductor already. When you wish you apply a different set of tap rules you are indeed tapping a tap in my opinion and would be a problem. Clearly your AHJ might agree or disagree but that's the beauty of 90.4.
Choosing the Outside Tap rule and doing what you are asking to do makes it very hard to comply with 240.21(B)(5) in my opinion :
(5) Outside Taps of Unlimited Length. Where the conductors
are located outside of a building or structure, except at the
point of load termination, and comply with all of the following
conditions:
(1) The tap conductors are protected from physical damage
in an approved manner.
(2) The tap conductors terminate at a single circuit breaker
or a single set of fuses that limits the load to the ampacity
of the tap conductors. This single overcurrent device shall
be permitted to supply any number of additional overcurrent
devices on its load side.
(3) The overcurrent device for the tap conductors is an integral
part of a disconnecting means or shall be located
immediately adjacent thereto.
(4) The disconnecting means for the tap conductors is installed
at a readily accessible location complying with one of
the following:
a. Outside of a building or structure
b. Inside, nearest the point of entrance of the tap
conductors
c. Where installed in accordance with 230.6, nearest the
point of entrance of the tap conductors