Toad hide?.....No
All your points are easily arguable and outright wrong, I'll show you why later,right now bit sleepy ,
Toad Hide!? Yes!
When Naruto and Gamabunta were fighting Shikaku the sand demon Gamabunta took a direct shot from shikakus air bullet and Gamabunta said even with my tough skin if I get hit with another one of those I'm done for.
My point being that Giant summons have very tough skin proven when Sasuke used Manda to shield himself from Deidaras blast.
Also when Enma the third Hokages Summon was able to withstand strikes from Orochimarus Sword of Totsuka. The only Giant summon that I would guess does not have tough skin would be Katsuyu Tsunades summon.
So are you telling me that a giant summon such as Manda or Gamabunta can take a giant blast from Deidara but not a stab from a puppet about a thousandth it's size!?
As I said before even if the poison did get into the toads system it would be like a cobra bite to Godzilla. No effect! That's if the cobras fangs can even penetrate Godzillas tough hide, Sound familiar? If so it's when I said Sasoris puny puppets weapons will not pierce Gamabuntas hide!
I believe that's a check mate lol.
Please please please "easily" argue that point.