Unless the Spanish and Germans curbstomp the USA in ASB or almost ASB fashion I can't see the USA tolerating any sort of permanent German presence in the western hemisphere. The Germans getting the PI, and the Marianas (which they did OTL) while the USA has Guam, Wake, Hawaii, and American Samoa is tolerable. The Spanish Keeping Cuba and Puerto Rico (at least temporarily) is tolerable. German ownership, co-dominium, or permanent bases there is not tolerable. IMHO Spain is underwater and going down for the third time right now. A continued Cuban insurgency, with continuing clandestine assistance form the USA will eventually throw the Spanish out. If the Germans attempt to tilt the scales with a large presence there - I suggest you look at the what happened to the French who attempted to take back Haiti in the early 18th century. Medicine in 1898 won't help the Germans against yellow fever.
Think Afghanistan with lots of disease - and the Germans have to supply their troops way far away. As their army is tied down there and casualties mount, their ability to influence events in Europe which is waay more important to them decreases.