As for the actual trapeze wire, they should be fine unless you find a guy weighing 500 lbs or so.
If you are talking about the possible problems with the shrouds and how much weight total is on the trapeze that is different. There is only so much weight that the side stays will EVER take because if there is too much pressure on the sail it will capsize the boat so technically the maximum load the shroud sees is the same regardless of trapeze weight. More weight on the trapeze will lessen the load on windward shroud.

Having a lot of weight on the trap will increase the stress on the forestay (the highest loaded stay by far because you are pulling on it with the mainsheet and also with the trap weight if you are back on the boat). There is also a large compressive force on the mast with that much weight on the wire.
When I did synthetic stays on a 18HT I made the top forestay out of a larger diameter than the any other stay because of the load it takes.