No crayons so far? 
This is my first pass at a pindicator attack, I haven't really thought about attacking Dreylin so much yet, except that we'll need lots of amphi units as his stack is on the coast.
Pindi Attack
The bad news is that Muirthemne's culture (shaded pink on this pic) prevents us hitting the stack with 1-movers.
However we can hit the stack with 2-movers by capturing Crow's Bridge. I assume Gate of Sorrows will have popped borders so will need a commando to take it. The orange arrows here are 1-movers, blue is a commando, yellow is our 2-mover hitters and some 1-movers to cover the stack. The red arrows are 4-move Galleons, the green arrow is two 6-move Galleons filled with Infantry.

Aha! But if we've got to Railroad we could combat-railroad 1N of Crow's Bridge to let our 1-movers hit the stack instead!
Depending on how many units are in Scales and Tallow we *could* capture both and reinforce them with the 2-movers that now don't need to attack the stack.
In the unlikely event that Pindicator doesn't build any more units, get any more tech or move things around we'll need 8 amphibious attacking units for the three coastal cities, between one and three commandos depending on how ambitious we want to be and 30 high-strength (drafted Infantry or C2 Cavalry) hitters to kill his stack. Then more stuff to move on Muirthemne and reinforce Scales/Tallow. So the very minimum we need is 15 Galleons but 25 might be more like it.
Fintourist's tech estimate spreadsheet gives us Railroad eot203 so I think t204 would be an excellent attack date to work towards! The only mild spanner in the works is if Pindi gets rifling in that window, but it looks like he's aiming for economic techs and Infantry deal with Rifles fairly happily anyway.

This is my first pass at a pindicator attack, I haven't really thought about attacking Dreylin so much yet, except that we'll need lots of amphi units as his stack is on the coast.
Pindi Attack
The bad news is that Muirthemne's culture (shaded pink on this pic) prevents us hitting the stack with 1-movers.
However we can hit the stack with 2-movers by capturing Crow's Bridge. I assume Gate of Sorrows will have popped borders so will need a commando to take it. The orange arrows here are 1-movers, blue is a commando, yellow is our 2-mover hitters and some 1-movers to cover the stack. The red arrows are 4-move Galleons, the green arrow is two 6-move Galleons filled with Infantry.

Aha! But if we've got to Railroad we could combat-railroad 1N of Crow's Bridge to let our 1-movers hit the stack instead!

Depending on how many units are in Scales and Tallow we *could* capture both and reinforce them with the 2-movers that now don't need to attack the stack.
In the unlikely event that Pindicator doesn't build any more units, get any more tech or move things around we'll need 8 amphibious attacking units for the three coastal cities, between one and three commandos depending on how ambitious we want to be and 30 high-strength (drafted Infantry or C2 Cavalry) hitters to kill his stack. Then more stuff to move on Muirthemne and reinforce Scales/Tallow. So the very minimum we need is 15 Galleons but 25 might be more like it.
Fintourist's tech estimate spreadsheet gives us Railroad eot203 so I think t204 would be an excellent attack date to work towards! The only mild spanner in the works is if Pindi gets rifling in that window, but it looks like he's aiming for economic techs and Infantry deal with Rifles fairly happily anyway.
Completed: RB Demogame - Gillette, PBEM46, Pitboss 13, Pitboss 18, Pitboss 30, Pitboss 31, Pitboss 38, Pitboss 42, Pitboss 46, Pitboss 52 (Pindicator's game), Pitboss 57
In progress: Rimworld
In progress: Rimworld