The guides I've tried out are only for testnet use, so I might check out moca's link in the near future. I can't quite say why I haven't been confident enough to try mainnet transactions, but if you're interested, this one seems to get a lot of positive feedback:
https://hackernoon.com/harnessing-lightning-for-instant-bitcoin-transacting-a-tutorial-3b9dcdc00552It's for how to spend on the Blockstream store, but uses Lightning Charge instead of (I think) c-lightning in moca's guide, so let us know if it goes well for you! I'd try it since the items there are only like $2 (and so far from what I read on this implementation, very high rate of success) but I am on a Windows machine (this guide is for Linux).