i wouldn't rely on the dome light powerwire to supply enough juice to drive one of those. small risk of overloading the wire and blowing the fuse. best to tap into a more robust power supply directly from the battery or fusebox's main powerwire.
more importantly, you have to determine how to attach it to the roof. you cannot/should not simply screw to the liner. ideally, you want to attach to the main cross member across the roof (roll-over bar), but this/these may not be suitable positioned for such a job. and if not, you will need to modify the roof structure to hold it.
so it's potentially a lot of installation work. but otherwise, it will work.
mind you, cheap ebay LCDs tend not to be very flash in terms of build and picture quality. though you're probably not expecting a lot.
also consider how much it will obstruct your rearview vision via the mirror.
