Thankful For Your Family…. Business?
Landscaping businesses are often family endeavors. While this can combine the best of both worlds (personal and professional), it isn’t always smooth sailing. Click here to read more.
Stop by a Ice Arena. The kick boards are at least 3/8ths thick and maybe 8" tall. The arena's replace this every couple years as they get black and kicked up by skates. Worse case they would be able to direct you to a supplier.
Otherwise they make poly snow plow cutting edges that are stiff and about 1/2" thick but it is over $150 for a 8 ft piece.
There is a material called AZEK that is a pvc type material. You can get it in 1/2, 3/4, in different dimensions. You can also buy it in 4x8 and 4x10 sheets. It is very durable but I don't know if it rigid enough to use as sideboards. Most lumber companies can get it for you, it is mainly used in home construction to make exterior products.