Absolutely right Herk. The two batteries I need are for starting my F350 Diesel thus the need for A BUNCH of CCA. Magically at Costco the biggest one was same price as deep cycle, about $80.
House battery that came with my Columbus is a combo meal deep cycle and engine starting. This is a compromise of each technology you describe above and compromises performance for a 5th wheel. What the heck engine are you going to start on a 5th wheel with no generator? As Herk said, buy a house battery that is deep cycle only if you have no engines to start on your RV.
You know all those labels that are on batteries, the company I work for makes the machines that put the labels on. Everything from small AAA batteries in a remote to large diesel semi truck batteries. There is only a few manufactures of rectangular lead acid batteries. Lead acid manufacturing plants are serious toxic/hazardous sites will all kinds of doo-dads in place to eliminate nasty stuff into the environment. Back years ago when we made the car/truck/semi battery labelers, most of this stuff was owned by Johnson Controls and they are still the leading manufacturer.
There are tons of brands of batteries however. All this is is taking the same friggin battery and putting a different label on it for each retailer, distribution chain, etc. Here is more info than you want to know. Lead-Acid Battery Manufacturers and Brand Names List 2013
You get what you pay for when it comes to deep cycle lead acid batteries. Myself, I go by how heavy it is - simply lift them side by side. Heavy = more lead = more run time between charges. You will be suprised the weight difference in the same group sizes. They look like the same size and power but the amount of lead will greatly differ. More lead = more deep cycle run time and generally the money you will pay.
Now if you are plugged into 120 AC power most of the time you use your RV you don't need a big expensive deepcycle battery. A smaller/lighter group 24 size would work just fine. The 120 power will be recharging your battery. RV camping when not plugged in, well now you want the big heavy group 27 size battery.
Go talk to someone that does walleye or bass fishing with the large Minkota, Motor Guide, Pinpoint, etc. trolling motors. Ask them wich battery runs the longest on the water and which one lasts year after year. Bass and Walleye boats take waaaaay more vibration and hard running abuse than your RV ever will. THAT'S the deep cycle battery you want in your RV if you are camping with no 120 volt power.
Again, pay attention to what type of battery you are buying for your RV. Herk is a living library of correct info, easier to use, and faster than one of those fancy new Ipads. Costs less too!