I’m really tempted to mount the block to the belt guard. That’s probably a dumb idea. I’ve got a 1 foot whip line for the block - I don’t really want to move the unloader back to the other side of the pump. But that probably makes the most sense.
Your belt guard won’t hold up to an unloader. I can’t tell what your trailer is made of but if it’s metal you have lots of options. I’d mount it on the other side of the pump. I’ve tried quick connects, straight nipples, 22mm and jic for the unloaders. I prefer jic but that’s just me. Let me know the length for your optimum set up and I’ll dig thru the barrel and see what I have.