How to hibernate MacBook Pro without a battery

I have a Late 2008 MacBook Pro, that runs only on charger (wall power), because the battery died a long time ago. With battery it used to be able to hibernate to disk, but it seems like I can not get that feature to work now, because the battery level never gets low enough to trigger the hibernation to disk - there is no battery.

I want to be able to close the lid and for the system to get into safe state, where I can remove the charger and later restore my work from were I left off, when I plug it in again.

After reading How to add hibernate mode to MacBook Pro and it seems like my only option is to switch to hibernatemode 25. This is quite old model so it does not support standby and autopoweroff:

$ sudo pmset -g
System-wide power settings:
Currently in use:
 womp                 1
 Sleep On Power Button 1
 halfdim              1
 autorestart          0
 hibernatefile        /var/vm/sleepimage
 gpuswitch            2
 sms                  1
 networkoversleep     0
 disksleep            10
 sleep                0
 hibernatemode        3
 ttyskeepawake        1
 displaysleep         15
 acwake               0
 lidwake              1

Is there a combination of settings that maintains the system state in memory but also always hibernates to disk that works on this model?

It turns out that my sleep image was somehow corrupted and system couldn’t boot from it correctly. After I’ve deleted it, all started working fine again: closing the lid and waiting for the light indicator to start pulsing, disconnected charger, connected it again and system restored from disk just fine.

Previously, I was been able to work around this issue by using DeepSleep utility, that was recommended as alternative approach on How to Hibernate a Mac.

When I want to unplug my MacBook from power I use DeepSleep to hibernate to disk. The resume then works the same like I remember it from when I had a battery in my machine. ¯\_(ツ)_/¯