Like I wrote in another post, anything "can be possible" but SP maps were really designed for SP purpose. They are not balanced in any shape or form. Bigger map like the one in Under No Flag could, maybe, with some stretch work in Conquest. Maps like Tirailleur are super linear experience and the attacker is in a really disadvantage position. These maps are also super narrow. Putting Conquest on them would probably not be really possible but maybe Breakthrough could work. Maybe.
Also, stated in the other post, SP maps have some technicalities in the back that player don't see like data streaming and other stuff that would need to be changed/removed/un-linked and yes, it would require more than just placing a couple of cover and dropping some flags.