I flip between tanks and blank WOW carts that I fill with my favorite flavor. A tank is easy to store because I can see the juice but a WOW cart is not as easy. If I filled a couple blanks and put them in a change purse to carry with me while I am out, would I have to top them off before using them. Also, what is the best way to carry them once they are filled....with the condom on.....with a drip tip? I am trying to save a little time while preventing having to fill them while running errands or burning a dry carto.