Your conceptual design combines elements of a SWATH (Small Waterplane Area Twin/Triple Hull), a high-speed multihull, and a TLP (Tension Leg Platform). Because its longest dimensions (70 feet) sit just under 24 meters (~78.7 feet), it straddles the line between recreational small craft standards and offshore commercial platform rules. Using Marine Aluminum (like 5083/5086 series for plating and 6061/6082 for extrusions/trusses) is the exact right choice for this weight-sensitive multihull.
A Naval Architect will likely reference a hybrid of the following standards due to the unique nature of your design:
The Standard: Multihull guidelines (like ISO 12215-7 and ABS) calculate what happens when one leg forms the crest of a 20-foot wave while another leg is in a trough. This creates massive twisting (torsion) and prying forces.
Design Impact: The joints where your three 19ft legs meet the 70x70x35ft triangular truss will be the highest stress points on the vessel. Because you are using marine aluminum—which is highly prone to fatigue cracking if permitted to flex repeatedly—the Naval Architect will likely require extensive cross-bracing and thick gusseting at these roots. The 7-foot enclosed truss structure will need to serve as a massive, rigid, three-dimensional torque box.
The Standard: Intact & Damage Stability criteria require vessels to carry their full payload, withstand winds safely, and survive the flooding of at least one watertight compartment.
Design Impact: SWATH vessels (Small Waterplane Area) have very low Tons per Inch (TPI) immersion. If your living quarters, massive glass, TLP winches, and solar exceed the ~18-ton buoyancy budget, the rig will sit deeper than 50%. A rigorous weight control program must begin on day one. Additionally, standards will dictate you place horizontal watertight bulkheads and "crash boxes" (collision bulkheads) inside the leading edge of those foils to prevent catastrophic flooding from a submerged log strike.
The Standard: Windows in marine environments (especially ocean-going or coastal ones) are governed by ISO 12216 and ABS criteria for Green Water impact and wind loading.
Design Impact: To have floor-to-ceiling glass on an offshore platform, the Naval Architect will have to calculate pane thicknesses that can withstand severe storm winds and potential wave strikes. The impact will be very thick, heavy, tempered-laminated marine glazing, and chunky aluminum mullions (window frames) spaced at calculated intervals to prevent the glass from shattering as the flat architectural walls flex.
The Standard: ISO and ABS have strict rules for "wet deck slamming"—when a wave hits the flat underside of the platform between the hulls.
Design Impact: With the top 50% (9.5 feet) of the legs out of the water, your underside clearance is 9.5 feet. This is generally excellent for standard seas, but high ocean swells may occasionally slap the underside of your triangle truss. The underside skin (the bottom of your floor) will need thicker aluminum plating and stiffeners than you might assume to handle hydraulic slam pressures.
The Standard: When parked as a Tension Leg Platform, the mooring lines are pulled tight to reduce heave, pitch, and roll. This implies pulling the platform deeper into the water than its natural draft.
Design Impact: To achieve tension, you must have excess buoyancy. For instance, if you pull the seastead down an extra 2 feet into the water, you create thousands of pounds of upward tension. The winches or cleats on the frame must be structurally integrated into strong-points on the aluminum truss. It also means you must design your total buoyancy to support not just the vessel's weight, but the constant downward pulling force of the mooring lines.
The Standard: Classification societies require that any appendages (like your airplane-style stabilizers or RIM drives) attached to the hull be designed with clear "weak links" or shear points.
Design Impact: If a whale, reef, or container strikes the 12-foot wingspan stabilizer, it must rip completely off the vessel without tearing open the watertight integrity of the 3-foot wide main leg. The trailing edge notch and pivot you described is mechanically elegant, but it must be housed in a flooded outer compartment isolated from the dry internal buoyancy volume.
Before you hand this off to a Naval Architect, consider the following tweaks to ensure buildability:
Your design represents a highly innovative blend of hydrodynamics and offshore living. Moving forward with Marine Aluminum and being proactive about ISO/ABS standards will give your engineering team an incredible head start on making this a reality.