Runners for ranger trailer

[artcarney_agr]

You can use high density plastic (HDPE) 2x4s and 2x6s - it costs more, but also requires more supports as it can't span the same distance as wood. Some companies add aluminum channel to increase stiffness to help reduce the amount of span needed, but even then it may still not be enough.

Your trailer might allow for use of it, but when I recently replaced mine it was going to take some additional brackets and welding to make it work on my trailer, so I instead just stuck with treated lumber and carpet.

Here's the product I was looking to use, the "Surpreme" has the aluminum channel added for increased stiffness:
https://www.ultimatebunkboards.com/

Also, some see it as a plus, and some see it as a negative, but if you use HDPE material they will be incredibly slick so you will want to make sure your bow strap stays hooked until you're in the water. I think of it as a plus as it makes loading and unloading easier and also helps prevent the boat from freezing to the trailer bunks when it's cold out.

[artcarney_agr]

Gatorbak is another option. You use treated wood like usual, but instead of using carpet you install the Gatobak plastic covers instead.

http://gatorbak.com/

Gatorbak is supposed to be a good option at preventing hull blisters on fiberglass boats.