Default fsx 737 logo and cabin lighting

I've spent a few days meandering through so many posts about the same subject (the hunt for the holy grail)

Ive FSX deluxe upgrade, sp1 and 2 installed so most of what we have out there based on Ye Olde box set is there now (not steam)

Some questions I have but can't find anything tangible to assist (forgive me if I've missed something but i'm now blurry eyed )

Everyone has the same issue with the default 737_800. Cabin light and logo on tail illumining by auto on dusk and night. Both work off the cabin switch -

Is there anything out there to tell us where the "logo light" is called from based on the action of the logo switch in the 2D cockpit. Im assuming its a xml file somewhere and a simple code. The logo switch does work where you have the winglet 737s, its not great but its a start

I know that the current logo and cabin light effect is a bmp in the texture folder (basically texture 0 folder) that can be painted out to remove the tail light white effect .

I've done that and now I have only cabin and cockpit lights on the panel switch - Ill live with that for now as they are to be frank closely related in their reason for use.

Ive mounted 2 lights (port and starboard ) of the tail against the fuselage, I've basically attached their on and off to function the logo switch - they work...........

So far happy days !! I now have the panel light working acceptably with the cabin and cockpit so close enough to acceptable function.

I now have 2 white spots approximately where they would in the real world case, their light to the tail logo. (even more happy days)

Now, Ive used the fx_vclighth and fx_vcligh lights together and placed these adjacent to the tail. They are called from the logo switch along with the spots on the fuselage (all in the light section of the aircraft.cfg file)

The effect is I have a very rudimentary tail logo light which is not effected by the time of day or the panel switch operation.

When I say rudimentary I mean that. its basic but functions for the purpose of trial and error

Now I can light and extinguish the logos via switch and the lights and effect are acceptable(ish)

Based on the function of the panel switch which basically turns on and off the b737_800_1_LM bmp file (makes it look like the cabin and tail light are on/off) my plan would have been to recreate a similar DDS image but just with the tail logo whitened to give light effect. Doing that instead of using the fx_vclighth and fx_vcligh lights would be easier to control shading (remove the wash out effect) and improve the realistic illumination. Its getting that bmp graphic to work with logo switch in the overhead panel is my issue. Any ideas if we can attach it to that switch , if yest Id be really greatful for some guidance. If its not possible because it all hidden in the mdl files then Ill go to plan B ------ I havent got one of those yet either