Tasker, SMS Backup+, and JuiceDefender: Working!
Ha! With experimentation, I've answered my own question.
The SMS Backup+ integration doesn't provide a *set* of commands that can be invoked by Tasker. But it apparently provides one default command: Backup. So if when writing a Tasker task, you select the Action Category "3rd Party" and then choose ""SMS Backup+", SMS Backup+ will perform a backup (i.e. it will post mail messages for anything new in the phone or SMS logs).
And I've figured out how to make this work with JuiceDefender.
The task looks like this:
1. JD APN: Enable APNs (set JuiceDefender to enable connectivity)
2. SMS BACKUP+ (post new phone or SMS logs to email)
3. Wait 1 minute
4. JD APN: Disable APNs (set JuiceDefender to disable connectivity)
I have 4 profiles to trigger this task:
1. SMS success
2. Received text
3. Phone offhook
4. Missed call
Note: For this to operate, "Third party integration" must be enabled within SMS Backup+ settings.
So far this seems to be working , although I haven't yet given it a rigorous test. I'll report back if I find anything amiss.