Hello, first post here.
I can install the Vbox 5.2.10 with OMV 4.x.
First i install the plugin with 4.14 kernel, after i add the sud repo in apt and download the vbox5.2.deb from vbox site.
I modifye de deb pack , removing the dependences and re-create it.
I run apt update and install the virtualbox-dkms from sid, it was build fine. After i install the modifyed vbox deb pack, and the ext-pack. Restart the system, enable the vboxphp and start the vm. I dont think it will work, but the vm start fine and runs great.
I can share the mode vbox.deb if anyone wants.