My Renegade doesn't have a curved butt plate (top) and would easily accept a slip-on pad, and my Cabelas Sporterized Hawken (bottom) came with a pad installed on it.
To make them even more comfortable to shoot with hunting loads, wear a clay shooter's vest with the built in pad on it too.
A Renegade or Cabelas can be found on GB for around $200 each, in a couple of weeks of watching.
('Just looked, and there is a Cabelas .54 on there now for $180 with a Buy Now of $195. It looks like a sporterized, it has the checkering on the stock. 'Cant see the butt in the photos provided.)