If you're going to the trouble, get a
crash tested harness. The
Ruff Rider Roadie is the only one I know, tho there may be others. I have one for each of my girls, and the product is a godsend! They have the added advantage of being able to get water bottle attatchments, collapsable water bowls, hiking packs, etc. You can attatch long leads, or just use the
lead that is actually part where the car seat belt attatches. Well worth the $$!! The "basic" is only $20.
Ruffrider.com | Dog Seatbelts | Car Safety Harnesses and Pet Safety
As far as the chewing thing? Mine have never tried. But you CAN adjust it so they are laying down. Much less chance of being able to chew it, perhaps.