Frogs are for the most part only sexable by calling. There are a few species that have dimorphic quirks, but I don't know enough about pacmans to say if they do. They're a little hard to breed, I remember there was an article in Reptiles magazine a few months back. If you wanted to get fancy, you could order plants from here:
springvalleytropicals.com
Antone, the owner, is a great guy and the plants are amazing, rare and exotic, as well as suprisingly cheap. Maybe not for this tank, but definitely look into that kind of thing down the road. Naturalistic vivariums can be rewarding to make and amazing to look at.