Started to tackle this project, got all the goodies together mostly bought from Autozone. Will be using 2.5mm2 automotive cable and will run dedicated pos and neg cables direct to battery terminals.
On the k75s, the most logical place for the relays is under the instrument damper. Will drill and tap into this weight for convenient attachment of relays. Easy from there to connect the headlight cables and make up a new H4 connector with 2.5 cabling. Wires will be black for both pos and neg so that it fits the rest of the bike and doesn't stand out,
Last photo is just a tip to store fasteners with their respective washers. Foam will work too but I had this old cat scratch pad which works perfectly in this case.