I don't think there is a way. Hopefully a newer firmware will sort this out.

Have you ever tried setting a timer to simply change channel in between the times of the timer recordings?

For example, if you have set 2 timers to record 6pm for an hour, then 9pm for an hour, what would happen if you set another timer for 7pm for 2 hours, but set the timer service to "channel" instead of "record"? Hopefully, that should keep the box turned on in between recording.

I haven't tried it myself, but it should work in theory!