if you have a good scrappy nearby, pull out the entire tailgate wiring loom and swap it into your car. it is actually easier than you think to get the looms in/out! I manged fine on 2 cars without even any string to help pull it all thru.in your case though, attach some string to the wiper plug and the 2 screen heater plugs. Take off the black plastic trim from the screen heater plugs or they wont fit thru the holes, just a clip to release em.
Pull it all thru, and fit the replacement! There are plugs behind the C pillar or boot trim somewhere for the tailgate loom.
other option is to solder in palce as said, or pull it out and solder then refit! Even if you disconnect the plugs at the C pill ar you can pull them all out at the tailgate end a bit to give you more room to solder wires and fit an uncut rubber bootay
