Brother, mine contest is even smaller than yours but somehow I manage to secure STEEM for the winners. I secure from my other posts where I'm getting more upvotes... & I have no sponsors for it.
Unfortunately, I guess, my theme is less popular cause most of the photographers do not like to stand in front of the lens but rather behind it.
Maybe it's not a good advice but maybe you could reinvest STEEM you get from other posts of yours... It's all I got. I'm not a big expert in the blockchain technology so I do not have any better suggestions.
PS
I like your contest & you have chosen some really amazing shots in this post! WOW!