I'm kinda bored and want to experiment with other tanks in the support role. Did a few games as Nautilus support and it works really well. Now i'm wondering about others...
Mostly 
Or are those picks unable to function properly with a supports income? I already know to go insane in lane and get the carry fed, its just how tank supports work.
Mundo,Maokai and Malphite can do fine as supports. For Malphite and Maokai I'd rush 
as a first item.
From experience, Maokai support is legit. standard righteous glory support build.
They all can. Every tank can support.
I have seen every one of those listed in OP as support and seen them all do fine.
After trying them all out. So far i've managed to make all but Mundo work (Mostly because I have little mundo experience to begin with)
Yea you can play tanks as supports. In my opinion they are the best supports , but the rely much more on there adc then squishy ranged supps.
Example. 
can just throw out bubbles from safety ,or 
can just spam q. While or 
have to dive into the enemy and if there is no follow up then your screwed.
Also worth noting is that tanky supports either have very little or no poke at all ,but excel at all in plays ,that can 100-0 the enemy adc. Unlike squishy ranged supps who prefer to poke and poke till the enemy is low enough to kill easily.
For gold just buy targons it helps with sustain in lane , gold income and tankyness
