Levels of politeness in Japanese, particularly when it fall to the derogatory forms shown in the OP, need to be looked at more on the whole than as a break down of each word.
While the term "kisama" may have the connotation of "bastard", you can't just plug it into each sentence and believe you've done a good job translating. A lot of people use different techniques, but the best quality I've personally seen is when the sentence structure and language of the character is used to denote their tone towards the listener, which may be marked by "temee", "kisama", etc.
Of course, you could still work in something like the term "bastard", but it needs to be played well. Used appropriately and in moderation, it's an acceptable edition. For example, if you're dealing with a character who has a lot of lines, and uses "kisama" in every one, just dropping the term "bastard", "fucker", "dick", choose-your-poison once in good context works well to accentuate the entire mass, without seeming like a "cookie-cutter" translation.
But hey, what do I know? /A/non can't speak 月語.