I am building a house and can not decide which size lot of 2. Need room to park rv next to house.PLEASE HELP?

We will be building a new house with a attached garage. It will be 40' feet wide and 48' feet 8"inches long and I love it but I have to decide today which lot I want to put it on. We have a 33' foot trailer but will be selling soon and getting a smaller one and we want to have enough room to park it next to house. It will have to go behind front of house but still directly beside house. One of the reasons I wanted a house was so kids could go outside in backyard and play so I want a swingset, small garden, and a deck in the back. We live in Montana and get plenty of snow and ice so if the house faces south the snow on the sidewalk would melt faster. The first lot is 70'feet wide by 90'feet long it faces South. The second lot is 62' feet wide and 120'feet long and faces East. The building envelope is ten feet in, what that means is that you can put your house anywhere inside including off to one side or set forward but you have to have at least 10'feet of room on each side. I do not know if the long lot would have enough room on the side for travel trailer or if the shrter lot would have enough room for a nice backyard. We need enough room in front for driveway. Please offer advice and opinions!!!!! Thank-you