My dad has a Phillippe Harlé Gros-Plant mini transat which has the same system to drain out water from the cockpit and his boat (a marine plywood/epoxy affair) doesn´t even have sea cocks... The hoses simply are driven in an "X" pattern from the cockpit floor to the bottom thru-hull plastimo plastic fittings (sealed with PRC aviation sealant) and properly tightened with AISI 316 clamps.
He never had any problems with the system...
If you make sure that you use proper hoses, fittings and sealants the communicating vessels law will take care of all safety issues for you
Pedro, from Portugal