The best way of dealing with this would be a box diorama.
Cconsider doing what was done for an IPMS Best of Show from a few years back.
The scene depicts teh crash between a North African Bf-109 and a B-17 where the tail of the Fortress is almost severed (think Memphis Belle scene) The various levels of depth were attached to several layers of glass which are not seen in the dio. Since you'd be dealing with only two layers, rather than verel to hold two aircraft and much debris, you're job would be much easier.
You could also force the perspective by using a 1/48 F-14 and 1/72 F-5. You could even push the effect by just having the nose/canopy of the Tomcat in the foreground attachded to the side wall and the complete F-5 attached to the rear wall by a rod out the fuselage to the back (this rod would be hidden by the fuselage and restricted angle of view). This method would eliminate the need for any layers of glass.
If you're going to be moving this around. I'd avoid any kind of thread as this will allow the models to bounce around and inevitably will cause damage to them.