Howard, it is quite normal for a generator's output voltage to be around 110 with full load. As Shadowcatche pointed out, 120V - 10% = 108V is generally accepted as the lower limit for normal AC voltage. My Generac in our old coach did the same thing at near full load, and the same thing with the Onan in the new coach.
50A shore power voltage should be higher than your generator output with the same load, the service entrance is rated at 200A minimum and, needless to say, utilities have a lot more generating capacity!
I'd say there is no problem, you're generator is working fine
The cheap meter will give you a rough indication of too much load. If I were you I'd monitor with it since you can leave it plugged in all the time but if you get concerned (voltage gets under 108 on it) get out the DMM.