I’m taking a stab without looking so I MAY be mistaken but this is how I understand the regulations.
Hook and line by definition is one line, one hook. The only exception being a lure with multiple hooks constructed to the lure itself………and I think that might even be limited to 3. If you tie on another “hook” anywhere on your line, I believe you’re in violation to the rules. Without the spin blade, I believe a crawler harness would be illegal. Another fly, by my perception, is another hook and could possibly get you into a rather uncomfortable situation.
Just 2 cents………….at half price.