Plumbers leave the job before the electricians start usually. Cut the vent pipe in two locations one 8" above the other and start 4 " below fixture height. Use ABS black glue - glue on a 45 deg plmg connector to each pointing back into the wall. Glue two 45 deg connectors onto the scrap of abs you removed after shortining it due to offsets. Take the leftover piece of vent and cut it in half. Now glue those into the saddle and glue the saddle back onto the vent. I wouldn't do this myself, but hey you asked what would work and I love to give sound answers to such riddles.:)
