I am aware from reading North South Skirmishers forums that some of those guys remove their breech plugs, maybe once a year. I do not know if it is a wide spread practice. One friend recommended unscrewing the breech plug, cleaning the threads and barrel end, and installing with anti sieze grease. This is something I have not done to my muskets.
I have a Thompson center Renegade and I called TC to find out if they sold a breech plug wrench, well not any more. They use to, I have a TC breech plug wrench for a smaller barrel than my Renegade, and they don't make that one either anymore.
I suspect that someone took a breech plug off, did something stupid in putting it on, and they were sued. I really don't know if pulling the breech plug is a good idea or not, but I would like to take it off once and see if there is rust or crud in the breech.
Wish I could provide a suggestion to an alternate wrench, but I can't.