I'd guess I'm semi-qualified to answer this. I've done back-end development almost exclusively throughout my career. I can change the background of your web page via css, which sums up my front-end experience. :)
I think this skill is just like any other: through constant practice you can become proficient. I'd say that if you were able to navigate the rigours of front-end-dev, you'll be fine working on back-end projects.
Pick a language, read a fundamental book, then start working on a real-world problem. Don't just do the Hello World examples. Create a back-end API for your todo front-end. Create a blogging platform from scratch. Then move on from there. What you'll find is that if you're solving a business problem you care about, you'll be better at solving it. Find a person you can work with who'll push you. Do a little project together.
Also, don't get too hung up on deployment or anything deeper than the web app itself. Use Heroku or Elastic Beanstalk to get your code running. I have friends who run very successful businesses with very little knowledge of how their stuff is deployed.
Just keep practicing.