Javier, in your 8" lightbridge, the dumbbell should be a pretty easy target, even in light pollution. The object is quite large for a planetary nebula, and absolutely unmistakable. (It is well named - it really does look kinda like a dumbbell in an 8" scope.)

A nebula filter can help with planetary nebula like the dumbbell, although you really shouldn't need one for this object - it is plenty bright. No nebula filter will help as much as driving your scope to someplace dark - although I totally understand the desire to observe as much as possible, and that means at home, even if home is really bright at night. (I did this for years.)

I'm sure I've seen it from Dallas in my 8" scope.

Good luck, and do let us know how the search goes!