In this conversion I took green stuff and made the bodies all-together larger so that the saddle wouldn't look awkward and the size would scale a little better. It was a little more time consuming but it works great! And the best part is it takes almost no skill, just lots of patience. You would just put the green stuff on his back, flatten it down till the top is almost just a millimeter thick and then spread the excess green stuff into the front arm down to his bicep, a little bit down to his belly, and then spread the rest into the FRONT part of the back leg. You can tell where I spread the green stuff in this picture:
Then with your modeling tools you just copy a Cold One without green stuff and make the shape of the muscles. Just lay a regular Cold One flat and its almost like copying a picture, you just follow the lines with your tool and on the biceps you just cut the muscle in half and round the two halves. Be sure to pay attention to which Cold One you are copying though! There are two styles of left bodies and two style of right side bodies. After thats done you just start poking at the green stuff making indents in the form of circles all over to make the scales. Now its important to notice that you need to extend the neck a little otherwise the body will be too large for the head. You just make a little tiny cube of green stuff connect the head to the body and shape the green stuff almost into a trapezoid so that it goes from larger (where the body is) to smaller (where the head is). In the picture above you can kind of see what I mean about the neck. AND the best part is, after you fit them together, make them the right size, and toss some scales in, you can move the head around a little, maybe twist it, and make the head sit how you want it! Maybe turn it so he's looking to the side or anything that comes to mind!
Now, like I said, it takes time. But you CAN do it! But the saddle looks fine as well, its just a lot more noticeable that the mounts weren't meant for the riders