Short splitter cable that can plug into the Battery Tender Harness with the old style SAE connector.
Splits from the SAE to another SAE that can plug the Tender into and a Coax Jack that will let you plug the Warm & Safe Heat-troller and Heated Clothing into.
Uses 16AWG wire, so it is safe to use with a set of heated clothing if the Tender Harness is 16AWG.
Warning: If you are going to do this then swap the fuse in the Battery Tender Harness with the one you received with the Heat-troller Battery Harness, so it will handle the draw. You need at least 15A fuse in the battery harness.