I do this for all my 24+/- sites with wan links and all. DHCP is on for each site, AD clients are happy as long as the config is correct.
Here is my dhcp server config on the MT
[firstname.lastname@example.org] /ip dhcp-server> print detail
Flags: X - disabled, I - invalid
0 name="dhcp1" interface=bridge1-lan lease-time=3d address-pool=dhcp_pool1 bootp-support=static authoritative=after-2sec-delay
I put my full domain details in so that the DHCP server dishes out all the settings. Like this working example...
[email@example.com] /ip dhcp-server network> print detail
0 address=192.168.0.0/24 gateway=192.168.0.1 dns-server=192.168.0.2,192.168.1.2 domain="yourdomain.local"
I remember doing this too, all I did was use the gui DHCP setup tool. Add the missing bits under network when you are done with the gui.
Hit me with questions if you like.