What do you think? Is this a good idea, or am I taking the wrong precautions

I think minimising risk where you can is good idea. But, if you're concerned about what's happening with Bitcoin, you might want to keep in mind options like USDT and SBD (both are dollar pegs).

If Bitcoin does make some sudden price changes then rest of the crypto-market will likely also be effected by it.
Choosing something that is self stabilising like dollar-pegged tokens is a good way to ride out a storm it also means you don't have to cash out to Fiat. However, Fiat would still be the safest bet from any potential losses.

Best of luck