Close OFP and reboot. Clean up your addon and other folders. (Ideally put all non-official addons in subfolders.) Open OFP and create a new mission on the island in question. Save.
Now open the mission with the problem. Copy the parts that work. Be very careful not to click anywhere near the problem area. Whatever happens, do not copy anything from anywhere close to, or in any way related to, the problem area. (Including AI units, static objects, triggers, waypoints and indeen the empty space around such things.)Paste into the new saved mission. (Use an object lined up on a grid line to get everything in the right place.) Copy script files, pictures, etc. into the new mission folder. Save the new mission. Delete the old mission. Reboot. Perform comprehensive computer maintenance, including defragging the disc. If you really want to be safe reinstall OFP but it shouldn't be necessary.
Create a second new mission. Place a single T80 and a player unit and make the setobjecttexture thing work. Expand until you have created what you want, testing at every stage. Check everything against the comref, twice. Check the pic itself, twice. Once it all works copy and paste into the mission.
In other words, treat the problem area of the mission as a virus. Remove it and start again. OFP goes mad sometimes: I've had phantom objects that are invisible and don't exist, but once they are deleted the mission doesn't crash anymore. Triggers that don't work until deleted and replaced by identical triggers are more common, though still rare.