Marble Ocean Outpost: 2047x Build Pieces (Small) this is very light instance-wise considering it's built on an ocean biome.

Required Mod to Place:
PlanBuild
Server Dev Commands (Placing the foundations underwater needs the noclip from this mod so your camera doesn't lock your view above seawater)
Structure Tweaks (to prevent build pieces from weathering)
Infinity Hammer (Building Pipette)

Recommended:
Infinity Hammer
Better Creative

Note:
>Structure placement using the mod might not be precise, it may place it higher/further, using infinite hammer may help you have more control in its placement.

if you have something to spare.
Patreon