RV Across Canada Halifax-Vancouver

I personally think that you really need to rethink your goal of around 300 km a day. You will have to drive every day at that rate, where as several of your stops will require a few days each. Without going into any details, some parts of your trip you will need to really eat up the miles as you will be seeing the same scenery out of your window from morning till night! As an example in Northern Ontario you might be lucky to see the Northern Lights! Stay up all night and sleep all the next day. I'm not that familiar with the prairies, so I didn't write much about them, but you might come across something that really appeals to you and may want to stay for a day or so. For example Banff & Jasper will need at least two full days and then only scratch the surface. Same with Vancouver, Stanley Park, Lynn Canyon, Chinatown, Gas Town, Little Italy, Museum of Anthropology, Grouse Mountain Skyride, Whistler, day trip on the bus, Ferry through the Gulf Islands to Victoria. You wouldn't want to miss any of that!
Ask more questions when you have a clearer idea of your itinerary. I came here as a foreigner many years ago so I do realise that people from other countries have a very different view of things from people who have lived here all their lives. Sorry I can't help you with your rental questions