I think the more interesting question will be how to hook up the new speakers. The OEM speakers have one connection with four wires. The OEM fronts are a dual speaker that somehow splits the four wires into two for each speaker. The replacement speakers are going to have only two connections. I have searched and never found how best to hook up new two connection speakers.
As far as your depth question - any name aftermarket will fit. The door has a mount that provides a good bit of depth.
I would simply take off the door lining. it is attached with only a few screws, the rest are click fasteners and then you pry off the lining with a large screwdriver. In only a minute it comes off. Then you can see all the sizes of the speaker.
i ended up running new wires to each corner as I didn't want to cut/splice factory clips. I replaced the monsoon head unit with aftermarket along with new speakers at each corner and didn't mess with an amp. it was a pain but well worth it as I can replace all original speakers/head unit if/when I decide to sell vehicle. there are write ups/videos as to how to run speaker wire thru door molex. the12volt.com also has useful info. and yes, there is plenty of depth in front doors and rear for almost any speakers.good luck