Several ideas here, most are not new but applications from 1/10 or other kits I've done over the years.
#1 The DTM uses silicone fuel tubing over the body posts as a stop for the body. This both cushions the body to chassis and keeps from scratching the inside paint from the body.
#2 Use this same setup on the DPR
#3 Bend the ends of the small body clips so that you can get a grip on them
#4 If you continually lose these little clips, attach the clips to the body with short lengths of fishing line