A puppy dog tray toilet is a good idea if you are trying to train a puppy. Keeping a puppy in a paper box is one way to start training but it does not pertain to teaching the puppy to go outside.
I am handicapped, so I've looked into this. It is beneficial with very small dogs, however nothing can replace leash and yard training. Even a chihuahua will overwhelm your pee-tray.
It's too much of a challenge for you to train the puppy to use the tray toilet. If it's a female puppy then you might have a little higher success rate. I would suggest you to train your pup to go outside when it needs to.
I've never found the puppy toilet tray necessary. In my experience, you just need to make sure someone can be home with the dog for the first few days. You'll have to take it outside every hour and praise the dog when it does "go" out there. Good luck!
