Potty training woes!

We're desperately seeking some advice on this one. Our little man is approaching 3 in a month and will be starting preschool that same month but they are requiring him to be properly trained by the start date.I feel like we were making some huge strides at the beginning of this year but then his sister was born and things became chaotic. His sister has a congenital disorder so not only has he had to adapt to sharing attention, but he has suddenly had to bare witness to a lot of family stress as we've now thrown a high needs new sibling into the mix.We've tried token economy charts and reinforcement schedules to no avail. We've shown him the long term reward of getting a new truck he's wanted if he could go everyday for a week. We've also tried the immediate reward system of continuous reinforcement (gave him a hot wheels car for sitting/trying/then just for peeing etc). He now flat out replies with, "No thanks. I don't need/want that" We've tried switching the reward to candy and treats and he still doesn't seem enticed.Another angle we've explored has been the 3 day potty training solutions where its proposed to have them wear underwear so they can experience what its like to be wet. Well my son is either super manipulative or intelligent, he doesn't wet his underwear usually and we've caught him pulling them down or pulling out his penis to pee somewhere else and then pulling them back up and moving on as if nothing has happened. We've set timers and continually prompt him after loading him with liquids but he usually refuses and throws a tantrum when he's asked to try.His main response to us pushing the issue has been "No. I want to be a baby and wear diapers" which I feel is probably jealousy related. He doesn't like sitting on either the small child size potty or the seat cover made for kiddos on the adult toilet.He's peed on the potty maybe 100x when prompted but still will not tell us when he actually has to go. He has yet to actually poop on the potty. My son is still going through the toddler phase where when he does poop, he runs and hides. My husband has been getting really frustrated with the poop situation and tends to yell at him for hiding. I worry this is going to have negative consequences later as he may just start either taking his diaper off to hide it or become constipated.The only thing we haven't yet tried is taking away his toys for non-compliance but I worry that's too harsh. I jokingly told my son that if he wants to be a baby then he can't do big kid things and threatened to take them away but now the husband wants to actually enact that policy and I'm back pedaling.I just don't know what to do at this point. Obviously we cannot force him to potty train but at the same time I want him to be able to go to preschool etc. He's a smart kid (probably too smart as he's already playing both his dad & I) and is meeting all of his other milestones.I'd love to hear some/all advice and what others have done :) via /r/Parenting http://ift.tt/29bp7gC