We seem to be converging on NAS from this thread, which i believe was about WLM originally.
It can be solved so easily - segregated inbound/outbound routes.
RWY12
Inbounds from the North
MSO - TRINA/NAMBA - WLM
outbounds to the north
WLM - NELSN -PLO/BANDA
inbounds/outbounds from/to South
Via an appropriate point SW for ins, SE for outs.
RWY30
Inbounds from North
MSO - NELSN - WLM
outbounds to North
WLM - TRINA - PLO/BANDA
ins/outs from South
opposite to rwy12
Clearances can then be issued to aircraft on the ground much easier, with just overflights to worry about - which can be sorted out much easier due to them normally in the cruise than nose to nose inbounds/outbounds.
And nothing prevents track shortening subject to the traffic.
Simples