I can tell you that my riggah mounts are SUPER secure, 1/4" 316L electropolished stainless steel backing plates

, but the 1-1/8" poles are somewhat too flimsy when towing 15" squid bars :shock: ! Luckily I had to use reducers to use these poles so I can upgrade them to 15' 1.5" diameter poles ... some year

.
Unfortunately, I've no experience with poles using spreaders, but my thought would that "if" stiff enough (no pun intended) ... less is more or simpler is better.
Here's why I like my riggahs mounted on the cabin top ... plenty of room to get around them FAST and get up to the bow ... if when on tuna and the Captain (that would be me ... unless I'm on the fish

) can't turn the boat fast enough.
FYI - this rigging connection using a fast-to-adjust barrel swivel to adjust the halyard length, ala Geo Poveromo, works fast and easy! I just use a wooden clothesline clip to fasten the up/down lines to each other so they don't slip. The release would go between the 2 snaps.