re-entry to US from mexico after time frame of current B2 visa

[aido]

I was wondering if anyone could answer the following question for me:
I am a B2 visa holder and spent 6 months (December 2015 - May 2016) travelling in the US. I recently came back to the US and was only issued 2 months this time, due to previously staying 6 months already. As I have my return flight from Vegas (to Ireland) already booked in December 2016 I am planning to travel into Mexico and central America from august, before my permitted time in the US expires and come back into the US to catch my flight in December 2016. Do you think there will be an issue if I leave and re-enter through the Mexico land crossing border?

[daggit]

Will be up to the CBP whether to question your third entry within a space of 12 months. B2 is for short visits to the US!

Sounds like you have a good bit of time on your hands.