I dont think the BX bucket even holds 1/2 cuyd. When I fill my landscape with mulch that was loaded with bobcat I get 2 or 3 cuyd at a time. It doesnt even fill the 8x16 trailer. It takes more then 8 trips going on the trailer and scooping up the mulch and moving it to where i need it in the bed.
I am not even concerned about ability to add a larger bucket. What I am concerned about is the operator fills the larger bucket to the max and lift it in the air all the way to get it in the truck that is high, if the operator is turning with bucket in air full of mulch, it gonna be very tippy. The BX has a very narrow stance. Mulch in the standard bucket is not heavy at all, adding a larger one would need to be custom made so its lighter and BX would need to have rears filled,add wheel spacers and add weight box. Also I would remove the metal bumper grill and make a new one that is car fender freindly. Sorry about the large winded post, but I am more concerned about saftey aspect more then the capacity issues.