Small Carrier Rockets: simple 56.5/m brick, from raws & self-proliferation. Dimensions: 124x79 With 16 on a planet, produces SCR ~900/m (and kills game's framerate on this planet). Power consumption: ~860MW (not counting 3x ILS).
P.S. Special thanks to the FactorioLab creators who make DSP late game accessible to the people like me.
Update 11-Oct-2025: Added 2x automatic pilers to the input hydrogen belts out of the ILS. When the "integrated logistics" upgrades are not yet researched, single unstacked belt out of the ILS was not enough to saturate the capricious fractionator loops. Added a belt and the automatic pilers to force at least 2x stacking.