I've had PT bunks with carpet on every tin boat I've ever had over many years with no issues in FRESH water.
In salt water, I've seen pics of guys who got light to terrible pitting over carpeted bunks. So if you go in salt often, you really want to lift your boat and rinse the salt out of the carpet after each trip.\
PVC downspout works well as bunk glide, too.
Going back to boat balance...
How much tongue weight do you have in your current configuration? It might not be too bad as-is, if the camera perspective distorts the picture.
With really light boats, you don't need much for them to track straight, but the more the better. You can put the axle as far back as you want and it won't hurt the ride, but might make it hard to move by hand.
In your picture the bunks are hanging very far off the back of the trailer. This tells me the trailer is too short for your boat.
You probably need a longer trailer otherwise you will not be able to get the needed tongue weight to tow it safely.
And I agree don't use pressure treated wood anywhere near an aluminum boat.