I love martinez. My buddy has a place out there. Ferguson is butter most of the day until some jack in a jet boat towing a tuber decides to get crazy! I haven't boarded at martinez lake yet, we usually go to ferguson and just out on the river. There is a place to rent trailers on the water at martinez for like $105 a night. It includes a slip and is right behind the bar! here is the link for them:
http://www.martinezlake.com/ I have stayed there, don't expect a five star by any means, just a bed, A/C, shower, stove. But you are right on the water, so it totally works. IM me if you have any other questions. My family is planning a trip again next month, maybe we will see you out there!