I agree with the possibility of confining him in a room with the box and his food and water. If he's urinating outside the box, that could signal a UTI. My aby sometimes defecates outside the box-but only when he is feeling spiteful.
All 4 of my cats are declawed and I never had any problems with them. Their feet don't hurt them-I can touch their feet. And they are the sweetest things-never biting anyone....if fact they love company and will snuggle up to anyone.