We used to haulmoose from rright near Yukon Border to Port Alice on Vanc.island and never had any problems. They were always cooled before we headed out and we put them in our utiliy trailer covered loosely with a tarp and then sleeping bags for insulation. Then we would take up any spare space with lifejackets bags of clothing etc, anything that would help insulate the meat and help keep it cool. You want to keep the meat dry at all costs andIf you absolutely have to use ice I'd suggest buying blocks and putting them in plastic bins so that the melted water can be drained off and never touches the meat. Good luck.
As others have said, we also used to drive through the night, switching drivers. We'd leave in the morning and usually the temperature would remain cool enough that far north for the first day. Next morning would see us on the first ferry out of Horseshoe Bay and we'd have the meat in a cooler by that afternoon.