alright, if your at the low end of light heavyweight then I would recommend you drop down to Super Middleweight. That weight class is easier to deal with than light heavyweight. Also its good that you know those martial arts but what kind of fighter are you? (submission, grappler, striker, etc).
Well I dont think anyone can deal with the pain of submission holds lol but you can train your mind to suppress it by having it done to you over and over again. Its more of a mind over matter thing.