So I went ahead and tried it. It actually worked out pretty well. I used a smaller critter keeper and put it against one side of the tank. I then put my broad leaf plant in front and wedged it in with the water dish. The critter keeper isn't at all visible from Puck's side of the tank. Puck never even knew it was there, not even when he was in his water dish.

The benefits: no escaped crickets (I feed him exclusively with tongs so I catch crickets one at a time and deliver them to him). The one cricket to get out of the cricket keeper ended up in the tank but that was the first time one has done that to me. But the best was that I wasn't worried about the transfer since sometimes they like to "drop" a leg to escape. Another benefit was that I knew the crickets were taken care of temperatures wise.

The cons: crickets don't smell great and they were making the tank smell bad. I didn't appreciate the fact that pacman frogs aren't smelly until a few days with the crickets.

Final decision: keep the crickets in their own container somewhere else but leave the space for the critter keeper open (and still blocked from Puck). Put the keeper in to the tank for feeding because that was really helpful.