Customizing Nginx Configuration in AWS Elastic Beanstalk

I'm running a rails application on Ruby 2.0/Puma instances and am trying to customize the nginx configuration. I need to increase the permitted request size to allow file uploads. I've found some other posts that have lead me to add this to my .ebextensions:

files:
  "/etc/nginx/conf.d/proxy.conf" :
    mode: "000755"
    owner: root
    group: root
    content: |
      client_max_body_size 70M;

That does create the file as expected, but it doesn't seem to work until I manually restart nginx. Because of that, I've tried to figure out a way to restart nginx with .ebextensions commands, but haven't had any success. Does anyone know of a way to restart nginx with .ebextensions or know of a better approach to solving this problem?