TO answer your question.. YES there are drain holes.
Though your generator may be different the only "Exposed" not waterproffed connerction on my Onan would be the 12 volt positive and water wont bother it.
But the compartment does have a hole. in fact about 4" in diamater. as well as some smaller ones.. It is how you cange oil filters on mine. Yours may be different.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times