Yeah that would work just fine, really. The dryer sheets are made out of the same flossy material that large air conditioning unit filters are made out of. Ya know those big flossy filters with the cardboard border?? That stuff works great too.
If you plan on getting alot of use out of your spoof and its more than just a one time quick fix... I would recommend using a paint roller and saying fuck it and buying the dryer sheets (which I believe you already have lol). The paint roller is sturdier than a paper towel tube, and its all fuzzy and comfortable :p
Oh and... I tore off small edges of duct tape and put them around the mouthpiece of the spoof for additional comfort lol. If you have a paint roller and put it up to your mouth you will see what I mean. The duct tape works perfect just like a rubber gasket lol.
Just grab two dryer sheets, fold them in half together, and use a thick rubber band to keep them on the one end. Put two more dryer sheets through the entrance and blow to push them to the end, take about a 3 or 4 square stretch of toilet paper, ball it up and put it in there, blowing it to the back again. Put another layer of dryer sheets in, and maybe another layer of toilet paper as well. For best results, always have the most outward layer consisting of dryer sheets.
The toilet paper is made of a more absorbent material and it serves to soak up the additional odors that would make it through the dryer sheet filters.
That setup will last about a month of smoking 3-7 times a day. The febreeze dryer sheets are the ultimate in superiority. They might as well say "FOR POTHEADS" on the box.