Good choice on the Rubbermaids, you're on the right track there, and it will make things a lot easier for you.
98F is WAY too hot though. A few hours at that temp will KILL both of those snakes. For sure. You need 90F warm side, 80F cool side. That's it. No room for error. Those are the temps that you HAVE to get the cage too. And that's why its better to calibrate all this stuff well before getting the snakes. Because in the meantime, the snakes are basically trying to survive through your little experiment. Its not really fair to the little guys.
90F warm, 80F cool. For sure.
Post pics. Lots of really knowledgable people here to help!