If the pads are the ones I have in mind of about 3" diameter then they are spreading the load better than the "clip-on" variety and are unlikely to damage the van.
However I would make sure that they and their rafter poles cant drop/move out of the correct location. With one of mine there were fabric loops sewn into the roof canvas into which the poles "hung", thus were unable to drop away or move excessively out of position.
Alternatively if the awning is not provided with supplementary bead for "clip-on" type pads there are moulded rubber pads that you sew under the bead of the awning. See W4's website; under awning and tent accessories; look for "awning pole bracket pads", these I found very good years ago. Cheers John.
Link to W4 : http://www.w4limited.com/