For my two dogs, I ALWAYS use their leash. Whether they're walking or hanging out at the campsite, they have their leashes on and I'm holding onto it. If I do have to use both hands for something, I will tie the end of the leash to the RV for that moment.
I used to use tie out cables like downtheroad shows, but found that when another dog comes harassing my dogs, the cable is awkward to use to pull my dogs out of the fracas.
I find that the 6ft reach is enough for the dogs to get comfortable, etc., but not so much that I don't have control over them at all times.
I never use a retractable leash. The first time your dog gets caught up in the middle of a dog attack, you'll understand why. It works great when your dog chooses to come back towards you as you call him/her - the leash retracts and you can lock it at the short length. But, when the dog can't or won't come towards you, it is pretty much impossible to safely reign the dog in. The rope portion of the lead is awkward and slippery to hold. The large handle is difficult to hang on to while you try to "hand-over-hand" the dog towards you. And when your dog is being attacked, you want your dog moved away - not you having to get in the midst of the fight.