FTP equivalent for pinkies and thumbs?

I've found the FTP to have a wonderful protective effect on my index, ring and middle fingers, and so I want to develop my thumbs and pinkies in a similar fashion to prevent/mitigate injury if I jam them. I can't really figure out how to do an FTP with the thumb/pinky since they oppose each other, so I'm trying to think of other options.

I'm thinking that something like a plank on only the thumb/pinky might work. Another idea might be to to FTP on thumbs only and then on pinkies only.

Anyone have ideas/suggestions?

i felt my thumbs get stronger than they were (they used to slide out of the socket every now and then) with good old fashioned finger pushups (the support kind) 

 

I haven't kept up with them since starting H1 but I just tried them again and they felt shakey(but i still could do a rep or two for quality) so it's been a while ( best i managed was maybe 2-3 reps of 3 finger assisted pushups) that's on the flexion side, as for extension, i have absolutely no idea what to do there apart from a thumb stretch with C-R.

 

i've seen photos of your L-sit on the ground and you seem to do them with finger support(from what i remember) did you have a recent injury that put in perspective the difference in strength between fingers? 

Rock Climbing Hand and Finger strengthening exercises