When we had our Familia I fitted them to the skirt rail to save drilling holes in the van. But we never used them as it is a bit hit and miss when fitted to the rail and the whole assembly didn't seem stable enough. We never found a location where putting the legs on the ground would have presented a problem.
Having had the canopy flip in a strong gust of wind just as we were packing up once, I wouldn't risk the wall plates again. That flip damaged the knuckle joint at one end which needed replacing and a new end fitting in the rafter tube. Make sure the feet are pegged down all the time or someone is hanging onto the leg. The plus side is all parts are available from Fiamma at not too outrageous a price.
Luckily, despite landing on the roof, the main tube did no damage to the Eriba.
We haven't fitted the wall plates to the Triton.