I would do what ever you need to do to insure an adiquate location for the TP. Whether you build a pony wall or have a free standing holder is up to you. But I vote for installation on a wall if at all able. The function of the pony wall can be improved by adding a pullout in the end, for storage. I've linked a thread with an example of Mongoct's pony wall with pullout. Here is a link that might be useful: Mongoct example of a beautiful pony wall w/pullout & TP.

cynanjon: Here's one. On that website when you search for bathroom hardware, 5 pages come up and each page has a couple of the open-ended ones. I was looking for Umbra specifically to find more of the ones I bought several years ago and LOVE. Not available anymore but I might have to try these open ended ones now. Think I'd mount them vertically just to make sure nothing rolls off the end. The one I have from Umbra has a metal bar the t.p. roll sits on. The bar sits in the side mounts. But it just drops down from the top and sits in. Has never popped up and out. Love not having to squeeze a roller to get it back in. Ouch! Lots of other manufacturers. I just wanted to find my old one by Umbra. Here is a link that might be useful: open end t.p. holder

I finally get fed up with the wiggly TP holder I got at Pottery Barn. It's just a bad design having one attachment point holding a horizontal roll with constant pulling and tearing. I found this one at Rejuvenation. It costs almost twice as much as the PB holder but it's very stable with two screws. It's also got much more heft and coordinates well with the other PB items in my bathroom. Yes, it was made in China, but it makes the PB one seem flimsy in comparison.

Agree that it allows for movement but it also makes it easier to change rolls How often do you use the roll, vs how often do you change it? and will allow my kids to change it when they use the last of it. If they don't change it, that's the (universal) issue, not the holder. Instead get a pivoting toilet paper holder. Would work fine, if the pivot is solidly/well made