Assignment of domain computers in EMS

I'm looking for a automated way of assigning different policies to desktop and laptop pc's in our network.

Currently I have configured a domain and see all domain joined computers. To differentiate between desktops and laptops I created 2 local groups in EMS, and assigned policies to each group. However, I need to manually move computers to the correct local group. I tried using Group Assignment Rules, but unfortunately these only work on Workgroups local groups.

I also looked into assigning 2 policies on the OU containing all computers using Installer ID, but that's also not possible.

So, as far as I can see there are 2 possibilities here: Create 2 OU's for desktops and laptops and assign the correct policy to each OU? Or remove the domain configuration completely and have EMS assign clients to local groups using Group Assignement Rules?

Any other options I missed? How do you handle assignment of different (type of) devices?