When Dweezil learned to escape, our first reaction was unmitigated horror - as he had been the WORST sleeper I’ve ever heard of, before or since, as a baby and toddler. And the only reason he ever fell asleep was because he was STUCK in there and would give up and lie down and pass out after a bit.
But we wound up getting him a toddler bed a day or so after his great escape. The first night was pretty rough - he kept trying to leave the room. When he finally got the idea he had to STAY IN THAT ROOM, poor kid was pretty upset. We had to take him back to the bed numerous times, and finally stand outside the door and hold it closed (that was unpleasant). He gave up after a few minutes. I went in a half hour to check on him, and saw him sitting on his bed looking woebegone. I tried saying a soft “nite-nite” and leaving but he burst into sobs. Poor kid was so bewildered.
He finally settled down (I don’t remember how)… and never again posed a problem, in fact his sleep IMPROVED dramatically.
OK, none of that answers the OP’s question; to that, I fear the only answer is “time to move on”. In the interim, put the crib mattress at its lowest setting and leave the rail down, so he doesn’t have as far to fall when he climbs over. If need be, put a gate over the door of his room so he can’t get out while you’re sleeping.
For the specific “rail height extender” - yeah, I’d be leery of anything out there. The closest thing I’ve seen is one of those tent thingys designed to keep pets out of the crib - and if your young’un is able to climb out, that poses more of a danger than having nothing there at all.
;).