It will be fine to transport a baby as long as he's healthy. Many babies get shipped across country and spend a good 15 hours in a dark box . I've transported babies to + from shows in the car on 4 hour drives ....as long as your car is warm you don't need any additional heat. I would put the heat on in the car to where I'm comfortable in a t shirt. The babies were in plastic or cardboard shoe boxes with no additional heat. They are better off cooler than too hot. A hot water bottle is not feasible, can slide or shift to crush the baby, plus it loses heat and becomes an unsteady cold water bed. The warm medical patch would work fine though. You can also buy hand warmers but they get very hot and must be wrapped in newspaper and taped so the baby can't come in contact with it. There are also the type of heat packs made just for shipping animals that don't get as hot. But really you don't need extra heat as long as the heat is on, but if you're in B.C then you might need a few heat packs if you stop to eat , but if you can take him inside with you [ have a smaller deli container with no heat pack if you do, then put in a bag or purse held under your coat ] then he'll be fine.