sam another go for warmth is,buy a little imitation webber from the 2 dollar shop
the small ones about 12 buckstake some fire lighter and some coal and small logs to fit in webber ,fire it up
and belive me u will be warm with out making a mess.and on the plus side u can alway cook up some fish u caught too.lol
anyway thats my advise ,and its a proven and tested way ,as i always use it in winter.ive had coppers on wharfs come up and they have never told me to put it out,just clean up when u leave