atv excursion help! 1st time in Cozumel

[spcruiser]

We will be in Cozumel at the end of March with NCL and I tried to pre book the Mayan ruins ATV Adventure and they are sold out - my husband and I really want to see some ruins and he is totally into Atv's so this is a must do combo for us but if the cruise line excursion which is our preferred way is sold out I was wondering if anyone knows of a place I can do a tour like this on our own - please help this was my husbands favorite excursion we picked and we are bummed it is sold out already! Do you think they will make more space once we board or should we try to book privately?

[ilv2cruis]

This is the excursion we are doing. http://cozumelcruiseexcursions.com/atvjungletour.htm

I couldn't get anyone to answer questions about atv's either