Capoeira, like I said before (and what e eryon else is saying), by saying:
"I will be using BJJ, Muay Thai, and Cap by the way..."- Capoeira
That obliterates the point of sparring with 'Masterless'. No one is doubting that your a "capable" fighter. If someone was, then you'd be justified to using KB and BJJ. However, since the intitial challenge is "capoeira is ineffective...", the only way for you to proove that it's not is to defeat 'Masterless' without using BJJ or MT or anyother MA.
I like how 'BlackBeltNow' put it:
"thats cheating. then if i wanted to advertise drunken boxing, i can like do wat i usually do (BJJ, MT, wrestling), then after i win, i can do a drunken form. then i give credit to drunken boxing."