We used a small squirt gun when our two were puppies. It worked on one, who loathes water, but the other thought it was some type of new game. Eventually (and a few books/sofa/pillows, etc. later) we found Grannick's bitter apple spray. One or two spritz near or on the object solved the issue. Good luck!
We have had great luck with the Walk Your Dog With Love harness and after a few early years of trial and error, it's the brand we have used for years now without issue. One of our basenjis can back out of almost anything and though we have extra limited slip collars, the harnesses are easier on them.Both our B's have been able to get out of the Ruffwear front range harness, but I have heard good things about their Webmaster harness, which has chest and belly straps. Good luck!