Yep - a 1.25 or 1.5 tapered butt plug will get you ready. I've used the large end of the Pure Wand anally and had no problems with a proper warm up.

I have only used the Pure Wand vaginally, so I don't know if I'd be any help.

Everybody has different sensations from the nerve endings there, so have you ever used other toys without it being painful? Or is this a first? Some people simply find anal painful period. Like I said, different for everybody. I would say try using the small end if you say the large end hurts... If it's painful, I certainly wouldn't force it or keep trying. That could definitely be bad. You could try relaxing more, if you weren't because a lot of people say that helps. It doesn't mean everybody will find it painless though. If you're set on doing it, I'd simply try the small end.

Also, the Pure Wand's small end is intense for me vaginally, the large end -- impossible to insert, so I can imagine it would most definitely be uncomfortable at least when inserting the large end anally. I think most people spend a lot of time with moving up in size when they're trying to get something of a decent size in there. They start off with something smaller, then when they're comfortable, a little bigger. So I'd get some lube, use the small end, then if it happens that it's not painful, then maybe try the large end afterwards. This way it's "warmed up."