There will probably be melt downs and screaming fits that will make you question your decision, but it is temporary and worth it. Typically after their initial die off their appetite becomes huge - eating you out of the house. Sounds like what you are feeding him now is similar to the intro diet and that's good. The best way to do it is clear the house of all the stuff he can't have, that way you can honestly tell him it's all gone. Also if it's not there you aren't tempted to give in when the going gets rough.
The decision to take the step is huge and must be done with pure dedication and determination. You aren't the only one here with a husband that didn't buy into this diet. The people here are fabulous and will help you. With out them I would have given up. Your child is worth it. I look at it this way, I can not sit back and let my child slide by because something may be hard for me. I owe it to him to do everything I can to help him and this is one thing that can help my child. So when he is throwing a fit and I want to cry right along with him...I suck it up and remind myself I am helping him not hurting him and because of what I am doing, one day he will be able to look me in the eyes and tell me "mommy I love you"....I would give anything to hear those four words, and every nasty pooh, tantrum, and tear would be worth it. If you decide to do this everyone here will support you.
This is my 3rd week of SCD and I was in the same boat. It took several days for my son to like to eat the foods and maybe a week where I didn't have to use "video reinforcement" as much. What I would do is ABA style techniques by setting up his table and chair with me next to him and call him over COME HERE and have him sit and have a movie on pause so he could see it. I would say TAKE A BITE and give him a bite gently helping him put a fork in his mouth on the very edge of the tongue (dyspraxia issues so tongue placement is an issue for us too) which he still thrusts out and if he got a little bit of food in LOTS OF PRAISE and played movie for a few seconds. Then pause again and repeat. There was screaming, tantruming, meltdowns gallore. My guy is an eater and I was so scared because he wasn't eating! All the foods I was doing on the Intro diet were foods he wasn't used to eating...eggs, meats of any kind, chicken broth etc.,
Fast forward to week three and I am cooking/baking peeled and deseeded zuchini along with hamburger patties and he is eating them up. He eats his scrambled eggs and his chicken pancakes (a favorite for the carb lovers!) I give a little bit of banana because it stops him up. Today I intro a pear or apple sauce. Slow and steady. I am not going to lie I was in a deep depression that first week because when he is upset, not eating, in despair my temperment seems to equal his...we are linked in that way. Now that he is eating I feel better. Just don't give in and you have to press on everyday. Hey email me offlist if you want to talk it through. I know it's hard with our carb guys!