Make peace with the Japanese, give them the Pacific possessions. Buy/trade for cargo ships loaded with coal, small arms to equip several light divisions, and room to evacuate all the troops and civilians to Ost-Africa.
Use the Marines and ships to capture Mafia and Zanzibar islands. This will make Dar-el-Salam available as the new base for von Spee's squadron. Just in range of the mouth of the Red Sea or the east side of the Cape passage.
Plus think what Lettow-Vorbeck could do with 3000 professional soldiers.
Promise Italy basically everything except the A-H lands to get them on board. Italians want Egypt they get Egypt, you want Nice, Corsica, and Tunessia no problem. Rinse and repeat for the Romanians, they want the land stretching to the Southern Buh and pound of flesh from the Serbians, can do. And again for Bulgaria.
Immediately send whatever troops you can scrape together and trap the Belgians in Antwerp or on the Left Bank as they retreat. Better yet sortie the fleet and remain radio silence until you are off the Belgian coast and land a brigade or two at Nieuwpoort. To take defensive positions along the IJzer. This would have the massive side-effect of forcing British divisions to stay in England.