Hi all,
Besides the "Gel-Kam", another good thing for the trays is "GC Tooth Mousse, a topical cream with bio-available calcium and phosphate", available through the dentist. Good for extra toughening. This is an Australian invention I believe, and made in Japan. Here it costs around AU$20 (with our dollar nick-named "the Pacific Peso", it should be cheaper up there!)
I also leave the trays when showering - saves time, whatwith all the other things you have to do
Cheers!
Tizz