not getting up in your biz or anything...but a cat will defecate right after eating, if he is diarhea free, you might try putting the litter box in a small room and put the cat in that room for about half an hour after he has eaten...he will get used to using the box again and will be able to still be around you quite a bit more...which will make him happier mentally. The chance of an accident is WAY low after half an hour from eating.
His litterbox has always been in the basement, so we keep his water bowl and food bowl in the basement, so he is always near his litterbox. He just used the box a little while ago, we made a big deal out of it....hugging him and petting him.
He's not locked in the basement 24/7, he likes to be outside (though he's an indoor cat) so we let him out into a screen house we have......he's zipped inside and can't leave, and we make sure that we spend time with him when he's there, so he's not locked away from us totally.