Other than getting clothes in the game at one of the shops, I have on one of 3 pirates, obtained only 1 piece of clothing from eliminating enemies.
I received an Orange pair of pants, for killing a navy veteran on the field at Kingshead.
Level 5-20 on grenades there, and I got the one pair of pants.
I've leveled 2 othe pirates there in similar fashion and never received any clothing (and yes it was after they added the clothing to the game).
For that matter I have a level 32 pirate, a level 40 pirate, and a level 25 pirate.
The level 25 pirate got the pants, the others have yet to receive anything of the sort.
Zeppers Lvl 40
http://pirates.teamofx.us