Not bad, really!
Just a hint. There are two ways that make positioning on a object fairly easy.
One is to use 3dsmax and vehicle import function, but as not everybody has 3dsmax, you can workaround. Use Editor42. Ed42 allows easily to even plant only parts of PCOs, unlike Battlecraft. Place e.g. the enterprise_hul_m1 or cockpit_external for other objects, then plant the spawners as you want (just use a static plane for that). Then calculate the relative distance of the enterprise_hul_m1 to the plane et voila, you have the exact position you want!
To make life easier, use an empty map and place the enterprise_hul on the maps 0/0/0 coordinates. Then you have no need to calculate at all, just take the absolute positions for the objects' relative positions 
.