SATCO Biggin,
As a possible answer to your dilemma you could adopt the method used one (single manned) night (combined Tower/approach) by a former colleague of mine.
TOWER: "ABC123, you know I don't have any radar"
ABC123: "yep"
TOWER: "well if I did have radar, I would now be saying to you "TRAFFIC 12 0'Clock 6 miles opposite direction similar level"" Imho a well deserved
DD