I used a larger tip (2mm) for soldering to the ground plane. That seemed to work well. Maybe the pcb design could be improved to help prevent this problem. Recently I got a kit from Sparkfun and for pins connected to the ground plane they had a isolation ring but with 4 small connections to the pad in a cross shape. This made the ground pin electrically connected to the ground plane, but gave heat isolation for soldering. Worked very well.
