You do realize that it's safer to rely on a stable external service than to run your own when it comes to mining? And by safer I am talking about your ability to actually win a block.

People often talk about bitcoin mining as if it's a race, which isn't entirely true. in reality, up to the point of when you find a valid hash, you are not racing against anyone, and your chances of hitting a block are independent from other miners hitting a block; however, once you do hit a block, the race starts. You need to make sure you propagate the block in a fraction of a second, mainly to other miners' nodes to let them know that you have already solved a block and that they need to start working on the next one. Other than that, it's possible that your block will be orphaned by another miner that has better connectivity to other nodes.

Add to it all the technical issues that your infrastructure can run into, like a small delay in downloading new blocks and clearning your mempool, and your getblocktemplate creates an invalid block. It takes a few components working together to ensure that your final constructed block is valid and propagated well and fast. everything must have 99.99% uptime, or else you are adding more risk for potentially no reward. You can't meaningfully have well-set-up mining infrastructure at home where your cat or kid may unplug the router power cable.

With that said, I do encourage everyone to test local mining for fun and educational purposes -- it's interesting to say the least, so good work you did there.