Many years ago I flew the F4 Phantom II, including the F-4E in Vietnam. Much of this info came to me at the F-4 Training school.

Regarding the F-4 Phantom II, if you will take a look at McDonnell designs, you'll notice that once that got past the original FH Phantom I and F2H Banshee, the rear fuselage was small diameter and extended out above the engine exhausts. The F3H Demon, their only single engine, as I recall, and XF-88 Voodoo were like this and had low flat stabs. In order to get the stab in better air for control at high angles of attach, the F-101 Voodoo had a T-tail arrangement. This had pitch up problems at high AOA. Since they couldn't lower the stab any more than on the F3H because of the fuselage design, they drooped the stab in an anhedral arrangement.

This worked fairly well for the initial proucdtion models, F4A & B, navy, F-4C & D USAF. Sill wanting more stabilator authority, they added slots on the leading edge of the USAF F-4E and the navy F-4J models. These increased lift and the E's I flew had much better elevator control on landing and take off than did the C's or D's.

It is also interesting to note the background of the dihedral tips. The original test plane had a foat, no dihedral wing. The sweep along did not give enough stability and it was determined that some dihedral was needed. Changing dihedral is not easy (except on RC planes). It requires both wing and fuselage modifications, both of which are costly. The solution was to add a wedge in the wing fold area to raise the tips to get the required stability. This was both easy and cheap so it was adopted rather than breaking the wing in the middle.

Left to right: XF-88, XF3H, F-101, F-4C