What is the best way to add filling in between layers and how thick

To me using a sturdy butter cream dam,pipe very thick butter cream out of a bag fitted with just an open coupler around the edges of the cake,is the best way to hold in you filling.

I forgot to add that I learned this from sugarshack's dvds she is a member here and has the best instructional dvds.

I am having to travel with cake about 30 miles away and worry that layers may slide with filling in there.

They won't slide ... unless you put in a lot, like 1/2" of filling or something. As mentioned above, I pipe the BC dam, then add the filling to slightly below the top of the dam.

The only slider I ever had was because I had too much filling (combined with the idiot who slammed on his brakes in front of me!)

Thanks so much. We always have to watch out for crazy drivers!!