Wearing mouthguard with temporary crown?

Here's the deal— I had two substantial cavities on the right bottom molar at the back of my mouth. My dentist prepped the tooth for a crown seeing as if both cavities had been filled normally, it would have caused the tooth to fracture. They placed a temporary crown on the tooth, and I am currently waiting for the real crown.

The problem? I'm a hardcore teeth grinder at night, and have so far broken two of the temporary crowns as a result. I've woken up both times in the morning and felt bits of the crown in my mouth each time, and had to run to the dentist to get new ones put on.

I've worn mouthguards in the past and have torn them in half over a period of a couple of months, so my grinding is pretty substantial. I'm trying to avoid breaking this new one I had put on today, and am considering boiling one of my dental guards that I have (I bought a two-pack of them a long time ago and have one left still). My question is, will wearing the mouthguard increase my chances of pulling the temporary crown off, or will the boiling/fitting it to my teeth pull off the temporary crown?

Obviously not using a mouthguard isn't doing me any good since I just break the temporary crowns anyway, but will wearing a guard put pressure on it to pull it off or make it come loose? It's a bit of a dilemma and I really don't want to go back to the dentist for a third time to get a new temporary crown; it's getting really inconvenient. It seems like I'm damned if I do and damned if I don't; I'll either pull the crown off or just break it again. I have eleven days until I get my actual crown put on.