Have a TME smoke system and was thinking about putting it into my Sig LT-40. Engine is an OS 40 LA with 10x6 apc. Have a design for preheating and it should work, according to TME directions.

Was going to go with a 4 oz smoke tank and enough batteries for a few smoke flights. Was also thinking about mounting the assembly under the aircraft in a removable tray.

Will this add too much wing loading or not?

Any comments will be appreciated.

Your question is kind of vague.

Investigate it a little further.
Have you weighed up all the gear you've mentioned?
How does that compare to your plane's current weight?

Weigh your plane and do the math to determine the wing loading.
Then re-do the math with your additional weight, and see what kind of percentage increase it is.

If you can post that hard data, it's more likely you'll get some feedback you can use.