What mac said. His are untreated. My old alumacraft someone restored the transom with pressure treated....the pitting in the aluminum was evident all over.
I used the Caliber trailer bunk wrap on my trailer. Holding up nicely but I am sure not as slippery as what Jon and Mac have. It was one of the cheapest options and on Amazon.
"Cost Efficient" Geoff.Because I know you aren't cheap.(Easy, but not cheap)