Our little chap is stinky as well, luckily he's old enough to be outside when he wants, the tray is in the conservatory and I open the end windows to let air blow right thru. I did wonder if it was the tinned food, he gets 3 small feeds of that a day then dry feed for afters and snacking on.
For the tray we use some absorbant granules OH uses, once dried out 'things' don't smell so bad, I reckon the tray should have some sort of grid so the pee goes straight thru to a container underneath, save throwing so much granules away.
when we first got him we had his brother as well, one of them went in a spare bedroom, as everthing is stacked in there while we renovate downstairs it took me till 3am to find it and clean it up, doors are now kept shut!