I wouldn't worry about it being strong...before you need to haul on the pelham to stop Louis, he'll have stopped due to lack of oxygen from a very tight throatlash (or throatlatch depending on your spelling preferences)!
One rein on a pelham?.....Sorry, can't see anything wrong with it at all. It's back to the old hands on reins thing again isn't it? Better this and some respect than a mouth bruised and bloodied by constant yanking on a 'gentle' snaffle.
Take the snaffle ring away and you have the equivalent of a weymouth. I ride in a curb with a longish shank and one rein everytime, it doesn't mean my horses are tearaways, or hard to handle, far from it, it is just what they are used to and are happy with.