Thanks for the recommendations y'all.
I've considered a second box, but not really sure where we could put one in this small house. Bathroom isn't big enough for a second one unless I were to move the laundry hamper to another room. Plus, the boys are trained to stay out of the bathroom - no kitty crunchies for them - but they have full access to the rest of the house. They are both so well behaved that we don't even bother to crate them when we are gone anymore. We just put a puppy gate across the bathroom doorway in case they conveniently forget their training while we're out.
I like the sounds of the SwheatScoop, I'll have to check for that brand when we go to the city. I know the wally world here doesn't sell it. Guess I'll experiment with the different brands y'all mentioned. Thanks again.