historical fantasy in RPG's and me

Looking at historical fantasy for a role playing game.

Recently I floated an idea of hooking the gaming group to the historic Lewis and Clark exploration of the Louisiana purchase. Using the expedition as an underpinning and plot hook, to get the players into the wilds.

The next step is to re-mystify the forests and fields from a time before “we” were all over them.
A straight up historic re-walking of Lewis and Clark would be interesting if well done, I just don't think it would be a heck of a lot of fun. I also don't think I am built for straight up historical reconstruction.

This is where a bit of research and “stretching the real” comes in. What were people afraid of in 1804?

How did they view the wild places of our continent? It will be my job as Gm to set a stage where those fears are real, and not simply imagined.

Another challenge is this. In RPG's walking is not fun, to say your party walked or canoed or whatever is simply not as fun or as descriptive as doing things. So I will have to spice up the travel and the the moving about as often as possible.

I am thinking the journals of the actual expedition would be a great thing to have. I am going to hunt them up , I Need to know what they actually encountered so I can make what ever the gamers encounter feel real , and then bring that extra fantasy element in behind that.

Also knowing how the party dealt with getting food , the elements and just generally living in the wilderness fro two years would be a great help. For example I know they used several native guides and the help of a trapper and his native American wife, so interesting NPC opportunities abound.

At the end of the day pulling off a campaign like that this one will require a bunch or research and a light hand.