You might want to consider joining QF FF instead of using AA. With QF you will get 100% miles on all sectors in M. But there is no Plat challenge available. You will also get a min 1000 points for any QF sector.

As for the 5 sectors in SWP, you may be better off just including the 4 legal sectors and purchase the fifth as a one-way flight on a different ticket rather than paying for an additional sector on the RTW fare. Someone else posted recently that the airline (I think I was QF in their case) forced them to pay for the last sector rather than the cheapest sector, so just purchase a one-way fare form the QF web site and don't include it in the RTW itinerary (and earn 1000 bonus QF points for doing so).