I guess the great tip is going to be, just fight it off.
What I found on my BX-2670. The drain is nothing more than a molded plastic pipe with a rubber cap held on by a hose clamp. Unfortunately, the clamp that came on the tractor is one of those squeeze types that suck in my opinion. In trying to get that stupid clamp off, I inadvertently popped the rubber cap off with the clamp in place. The lip on the end of the drain pipe is really miniscule. That was the hardest part. The second hardest part was finding where that dern thing went!!!!
When I was done, the cap easily slips back on the drain pipe. For a clamp, I used a regular screw type hose clamp. Using a socket, on a long extension, and a ratcheting screwdriver for a drive, it was fairly easy to put the clamp in the socket, stick it in there and place it using a finger by feel only. Then just tighten. Any future times, it'll be a simple matter of using a socket to loosen the clamp, take it off then easily slip the rubber cap off.