Yes, if you use F4 to assign back button focus to the AE-L/AF-L button and save that to a User bank, then use F4 to assign AE-L/AF-L Lock (or some other function) to the back button and save that to the other User bank, you will be able to switch between the two focus modes (BBF & half depress of shutter release) by switching between the two User banks.
Another option is to put the camera in M, A, S or P and use that as either a variation on your BBF mode or as your half shutter press mode. For example when out photographing birds and wildlife, I setup User 1 for high shutter speed photography of BIF, User 2 for slow shutter speed photography of perched birds or stationary animals and Manual to create a variation on one of those themes.
In this way, I effectively have access to three custom user settings: U1, U2 and Manual. You can do the same in S, A or P mode.