Okay, if it's happening that rarely, my personal preference would either be to monitor her drinking and make an extra pre-bed walk to really empty her on days she's drinking more, or teach her a signal to go out that will be able to wake you up at night, like hitting a bell. I'm a light sleeper and have the dogs in my room, so when someone's shifting around, whiny, scratches the door, or is otherwise unsettled, it's easy to get up and let them out, and they both like their sleep enough that they don't usually disturb me unless they really do need something (well, the younger one took a bit to get there - we did go through a "I want to sit outside and sniff the wind at 2AM" phase when he was a puppy).
If you do want to offer her an indoor potty spot, my preference is something like the Potty Patch fake grass style setups, or more of a litterbox with low-dust newspaper or wood pellets. Something that looks and feels nothing like anything else in your home, and with sides that make splashing and aim issues less likely. If she's a bigger dog, this will require a good bit of dedicated space to make sure she can comfortably use it without the risk of sticking her butt over the edge. Puppy pads, in my experience, are too easily confused for rugs, bath mats, a shirt accidentally left on the floor, etc., at least when it comes to using them with baby puppies. I'd try setting it up outside first (or bringing it out whenever the weather allows, if it can't get wet like pellet litter), and encouraging her to pee in it until she's using it comfortably and regularly, then move it inside and either keep a little pee in it or keep some soiled litter. That way you're not spending money on products, and it smells like HER potty spot, not just any generic potty spot.