There are no 12 volt true deep cycle batteries sold at stores like Wal-Mart. That's why many of us are using golf cart batteries in series to get 12 volt battery banks. I'm running 4 of them in my 5th wheel. After my experience with a 12 volt Optima in my truck camper, I no longer wish to waste my time with so-called "RV" batteries. They don't last.
Although my trucks don't have room for these golf cart batteries as starting batteries, given that I have four of them, I bet they would start the truck just fine. They are perhaps not ideal for the load of starting, but with all that plate area, they have plenty of juice for starting if I had to use them for that.