I was in Lowes today and in the back of my mind I am on the lookout for something different for track barriers on a temporary track for our club.
Ran across some vinyl rain gutter/downspouts that caught my eye. Looks good and the connectors and 90 and 45 degree bends look pretty seamless so it should not catch on the cars. The downspouts might work as they are about 2" x 3-1/2"....+or- and it comes in 10' lengths.
The first problem would be corner marshalls stomping on it...it would likely crush. I think you could take a 2" x 6" x 10' and rip it in half and slide it up into the downspout...can't crush it then and the weight would hold it in place.
It would not need painted...no splinters....looks awesome.
The U shaped gutter could possible work upside down and also with some dimensional lumber underneath....almost an RC version of the soft wall
The mfg is Raingo...if you are ever in Lowes...or probably Home Depot take a look and see if I am crazy.
The downspouts are about $7.50 for 10', give or take...the gutter is about $5.00 for 10'....so I don't think it would be hugely cost prohibitive?
here is a link to the downspout at Lowes