Flat on the ground

I am trying to make some Airfield Numbers, signs etc to place on TOP of the tarmac or other surfaces. What is the Hight or Depth they should be??? the ones I have made are Always too Thick and the planes "sink" into them. I need real "thin" objects so they look like "paint" on the tarmac....If you can give me a hand I'll appreciate it since so far I have had no luck...
Thanks guys...

I do use ADE to make airports, But, I also make "airfields" without it where I need to place the runway numbers as well as other ground markings, this is where I need separate objects made with FSDS.....How are you Jean? long time no see.
Very well thanks.

For a "tic-tac-to" game in parachute center (in my CSR3 Victoriaville scenery) I used a flat polygon with transparent texture. I putted it some pixels above the ground to avoid flickering.
gp in ADE will cover up taxiways, unless you use exact texture of taxiway being used. cna be done and done nicely but much easier, why not make your numbers or letters in your paint program however you wish, then with DXTBMP do the alpha thing, save as dxt1,3,or5. Then in FSDS choose 3 side poly - change to 4. ad trans as material and texture your letters or number you made on it, add it to a library and place it. Fast- easy, and as Pete Rose once said... no runs, no drips, no errors.

I did this with my alameda sceneery (never released cuz friend is scared of stuff. and in my aurora sceneery about to be released. The words ALAMEDA and AURORA are right on a taxiway respectively. Looks great. No flicker. One of the easier things I have done. bob
Um I just noticed that I posted my comment in the wrong thread. Must've had too many tabs open. I don't know what this is about, I don't know anything about FSDS or if my comment helps you with your problem. sorry.