Anyone breed larger plecos?

[CHJ]

My female Gibby has what I suspect is a "love bite" on her tail. The raw area is as big as the male's mouth. He continues to try to cuddle her but there is no cave in the tank.
I was thinking breadbox for a cave but on looking at the fin spread on the male maybe 8" PVC instead? I can end cap those and melt them a bit in the oven to get the cave shape then rough up the inside with sandpaper or sand and epoxy.
Is there a better cheap cave idea that I'm missing?
Any concerns specific to larger plecos breeding? I'm guessing any clown loaches that rush into the cave could flee it just as fast. I will move all the drift wood to the other end of the tank to attract them away from the cave. I'm guessing the yoyo might risk the pleco for some tasty eggs but I'm hoping it will not.

 

[CHJ]

Well we decided to come up with a cave. I'm not sure if they like it. The female spends time in it and the male likes to stick his face in it and block most of it off. It is about the right size. Not sure if they like the color of the bin.

The Clowns like to head into it and bolt when the plecos return. One of the Dats also tried going in it.

 

[CHJ]

Well the female spends most of her time in the cave with the male trying to block off the front of the cave. Unfortunately for breeding several clowns like hiding in the cave as well as one of the dats. May have to try PVC pipe instead.