There are very few Mosquitoes that were built to be solely used cat rigged. "Red Alert" is the only one I've come across. If you put a sloop bridle on one of these boats you will probably break the bow off. They have been built very light in the bows so they dont have much strength against being pulled in toward each other.

Having said that even Red Alert survived having a spinnaker added.

I believe the loads on the bows of a cat rigged boat with a spinnaker are not as large as those on a standard sloop.

If your boat has a high bridle then, if you have any doubts, it's best to leave it that way and suspend the pole and chute below it. Rather than change to a sloop bridle.

Any old timber boat needs to be watched for rippling on the inside face of the hulls near the front beam. That's the warning you get that the ply is losing it's strength and is about to collapse.