+1 for the sliding. version. It can occasionally mean you can swing the stern without your engine also having to tug the tow 2 foot aas well. I've used a super smooth rope for my bridle - saves a carabiner onthe tow line taking the paint off my engine leg when the tension comes off!
+1 for the carabines, except I have a soft eye one side, carabine spliced to the other. I have 2 eyes on my transom that double up as holding the A- frame on.
The soft end has a spinnaker snap shackle fixed to the u-bolt o nthe transom with a release line that runs forward fixed to the replease pin. I installed that mod after a nasty incident with a yacht whose skipper was too busy watching the scenery and resulted in me being towed backwards by him taking the tow sideways faster than I could correct for it.
I use spinny snap shackles becase they will release under load.
Floating rope will also help keep it out your prop, but if your anchor points are not too far down the transom then you shouldn't need too much slack to allow the engine to tilt.