trim monokote is thicker than the regular monokote, It is good for repairing planes that have sticky covering like Tower Trainer but other than I personally don't like to use it.

And the size is not suitable to cut big letters.

For the 4th plane for 3D profile I recommend either .25 size Fat Free Taco by Paul Swany there or 40 size brother buritto, I have FF Taco and it is great for 3D and It is tougher than you expect.

bigger is not necesarrily more expensive for 40 size buritto will be ticket in which you can use the standart servos and 46bb engine which is a little expensive than the 25FX. but you will save on servos.