The key to making Sealion work is to play aggressively with the japanese against the US. This way the Germans will be able to prevent the US from retaking London.
Here is my suggestion:
G1 Buy trannies and a destroyer to protect them. Sink the Royal Navy in sz 106, 111, 112. Don’t attack USSR.
J1. Buy trannies and a artillery.
Make a few moves against China, but don´t attack anything else. Move the all Tokyo warships to the seazone containing Midway. The navy sz 19 and 20 moves to Tokyo and incoming transports unloads on the mainland. Move the Tokyo Planes to Solomon Island together with a transport.
G2. Buy Trannies and units for g3 Sealion. Attack the remaining UK navy and invade Scotland.
J2. Buy an AC and some other naval units. Attack Pearl, Solomon, Guam, Philippines and Kwangtung. This way neither UK or Anzac gets any bonus while gaps is gaining 10 IPC. The US income is reduced by 10 for loosing the Philippines and Hawaii.
G3. Invade London and start the war with USSR.
J3 Head for Anzac.
If this is successful the US will be spread to thin. The Japanese only needs one more victory city to win and London is captured. This gives the Germans enough time to deal with Russia alone without the US occupied in the Pacific.