Hello and welcome. Congrats on your purchase. I love popups, and have previously owned one. We didn't have the the toilet option, we used a separate portable potty. I would suspect they would be near the same in size. We got a whole lot more uses than that before it needed to be emptied.
Not sure if they are the same, but you will only find out by trial & error!
Pete (Jolly Mon)
2018 Wildwood Grand Lodge 42 DLTS
-Seasonal Space, Northern MN.
-2017 Sylvan 8522 LZ LES/115 Merc/Sea Legs