You ever tried incense to get the smoke effect? I got a huge bag of incense cones off ebay for silly money. They're about 1 inch high and cone shaped (funnily enough) with a base of just under 1/2 inch wide. You stand it on its flat base, preferably on somethng that wont burn or melt, light to tip of the cone and once its smouldering nicely blow out the flame. The cone will then slowly burn down giving off a good amount of smoke. I'd estimate they take about 10 mins to fully burn out.
1 cone probably gives off the same amout of smoke as my HL Stug3... but of course as these fellas are chip as chips who's gonna stop at just 1 cone
I was thinking to work them into my Sturmtiger build using a smoke box but they would be perfect to use in a stactic, burnt out tank and very easy & cheap to do. They smell a lot nicer too.