Assemble all you can in the Kanto or maybe in the Echizen-Noto area and be the shadow of the approaching Uesugi, they should leave the provinces behind them quite undefended...
Grasp what you can in the Kinai or wherever, usually Kyoto can be left unguarded (due to its settlement bonuses), I think you can manage to halt the Chosokabe at Harima, merging your half stacks, while gathering all you can to stop the Uesugi, if possible at your best castle in the vicinity...
It will have to be a rush for the victory conditions :P