Buck, your situation involves a VFR tower, which means you don't apply IFR separation, just visual. I'm assuming that you have some sort of FAA TRACON or Center dealing with your IFR Arrivals/Departures, which in your case some assurance should be given that you are in fact going to apply visual between the two A/C. (LOA's, SOP's, verbal confirmation, or whatever your facilities boss decides) Basically make sure that you are giving one of the A/C restrictions and keeping positive control you'll have no problems. This is one of the things that I find most difficult for prior military controllers to adjust to in FCTs. I know it was really strange for me, in the military most things are sequenced and sent to another reporting point.