just with the "background-mode" plugin only?
I thought i only needed that while I programmed with my device plugged in via USB to debug.. I noticed Android started to close the app when in background mode only while NOT plugged to computer via usb. That is why I modified the power management plugin to get everything working all the time!
About the reboot : I never tried to do that !!! but i just did a google search for "cordova app start at reboot" and found this : https://github.com/ToniKorin/cordova-plugin-autostart
Did you try that? please tell me what you think about it 