Well.. there's nothing inherently wrong with putting a smoke system on a Cub... but you may be in for more hassles than you expected.

Smoke oil likes to peel the iron-on coverings loose. You have to seal the seams by painting them with clear Lusterkote or some ter fuelproof PAINT that will stick to the airplane's covering.

You have to either buy a smoke muffler, or tap the original exhaust system at a high temperature, low pressure location (as close to where the headder enters the muffler as possible)

It helps to wrap copper tube around the header to act as a pre-heater for the fluid.

TME makes a decent smoke system kit. Retails for about $90. Then you need a fluid tank which can handle the smoke oil. DO NOT use a Sullivan tank that is not rated for the oil... the plastic tank itself will soften and soon will leak. Make sure the tank's stopper is rated for smoke oil too. (Sullivan sells a separate gasoline and smoke oil stopper kit)

The Tygon tube used for smoke system plumbng loves to slip off of brass tube. I take 18 guage soft copper (solid, not stranded) wire and wrap the connection then twist the ends to squeeze the tube TIGHT. I pull some of the end of the twisted wire and wrap around something to make certain the tube can not slip free.

Power the smoke pump with a 5 cell pack. (its rated for more so Its OK) 4 cells won't overcome the muffler pressure at full throttle.

Purchased smoke oils tend to be less messy than home-brews. Super-Dri works great. You can mix your own from corvis oil and kerosene. (about 50-50. Some people will have experimented more and may have a better ratio, but this works)

Aside from that... follow the TME smoke system kit instructions and it will work.