No problem adding a smoke system. All you need to do is move things around for the second tank and the pump. Depending on your throttle servo you might be able to belly a pair of 16 ounce tanks togeher in the tank area. If you're not running a pipe you might be able to do an over/under installation. Keep all the added stuff as close to the wing tube as you can to avoid a CG that changes as smoke burns off. Things can get ugly when that happens.

To make a smoke muffler all you need to do is add an inlet nipple to the muffler close to the exhaust port.