Glock 42? Sounds a bit outdated. I carry a Glock 43 and find it very comfortable. It is only a 5 round mag but if I need more than that I am either vasty outnumbered or need more range time.
The G43 is our new single stack, 9mm pistol. The G43 is the most highly desired and anticipated release in GLOCKs history. The G43 is the answer to your everyday concealed carry needs. It’s ultra-concealable, accurate and fantastic for all shooters regardless of hand size. The grip has a built in beaver tail design which allows the shooter to acquire a high and tight grip. The aggressive texture of the grip lets the shooter more easily operate the pistol. The large magazine catch allows for easy removal of the six round magazine. Engineered to the same standards, the G43 can withstand the same tortures as other GLOCK pistols.
https://us.glock.com/products/model/g43
You can have your spare mag be an extended mag
I have both the Glock 42 and the Glock 43, and they both have 6-round magazines.