> the high-poly to low-poly bake isn’t turning out well
This may depend on how you generate the highpoly and lowpoly models.
According tileable textures:
Well this depends on the texel density you want to have and also the "additional details" across an opject.
For your big main cylinder tanks you could certainly tile some map three times arround but you need some more distinction in the up/down direction ( or whatever you call "..-up") ? This maybe is even more important for the pipes..
With "additional details" i mean: if the "tanks" are covered with details then the up down repeatition/tiles are not so much visible and may not need this (?). Or you rotate them and the seems is covered by some "belt".
For generating tileable textures: generally one want to generate or blend this in a repeated way so one can "cut out" a tileable texture inbetween. There are thousand of tutorials and plgins/addon and even applications for this.
Replies
https://blenderartists.org/t/tileable-texture-and-rgb-mask-workflows/1564787/2?u=okidoki
Maybe this might help you.