You asked about the gap liners, it is way cheaper making your own. Go to Lowe's/ Home Depot and look in the carpet section. They sell 3 foot wide rubber runner by the foot.
For your front, remove the stock ones and use them as a pattern to cut new taller ones. For the rear, if you really want them there, just cut them to cover the area and screw it into the pinch weld (that is how the pre made ones attach also).