Can't I completely avoid the blow off tube by brewing less beer (forgive me)?
I'll only be using primary (6.5 gallon carboy) and if I brew a smaller batch, maybe 2-4 gallons vs the 5 that the kit came with, wouldn't this eliminate any chance of an explosion or stuff coming out of a blow off tube?
While this may be sacrilegious, there is no way I can reasonably drink 5 gallons of beer is short order. I also like the idea of smaller batches for less bottles to clean out, brewing more often, etc.
If you keep the temp under control (mid 60s) and you put only 5 gallons in a 6.5 gallon bucket you are likely golden on the blow off front. Most out of control blow off situations come from too high fermentation temps. you might get a little krausen (the foam on fermenting beer) out the top of the fermenter or thorugh the blow off tube/airlock but it will easily be contained by the cooler.
smaller batches are great, a lot of folks on here brew 2-4 gallon batches. However, I think you will be surprised at how quickly 5 gallons of beer can disappear when you brewed it yourself. and if you keep it cool it's good for months (depending on style) or years even. I have about 2.5 gallons of a barley wine I brewed in early 2011 still in the closet and it just keeps getting better.