If theyre fitted securely i dont see any reason why they wouldnt pass a test but…theyre going to be pretty heavy and being wood they’ll surely succumb to rot eventually plus the outer finish being grain wouldnt look anything after painting.
Genuine side skirts are not exactly cheap and if its down to cost there could be another option of 3mm sheet plastic. Strengthened up at the back/ top/sides with lengths of ali angle bonded to the rear will work. You’ll have a far better painted finish as well. Possibly an idea… 