SSI + content-length headers

[Rajwinder-office Singh <rajwinder.makkar.office@xxxxxxxxx>]

I have a situation :

1. I have to keep SSI enabled on all *.html pages.
2. SSI removes content-length + Last-modified headers from *.html
3. I have to keep these two headers for it to be cached by my CDN provider.
4. No fun of using XbiHack cause every other html is having ssi.

Does it make sense to calculate these two headers and then insert both headers in some kind of output filter ?

Or is there any way to disable this behaviour that apache do ?

Thanks
Singh