Trike
Ten mile limit at 15mph? Wouldn't you be through riding in about 45 or 50 minutes? If ya really wanna go somewhere it better be close, like to the store and back for a six-pack.
I think you were on the right track with the front friction drive idea. You could pretty much hook up a weed whacker motor that way, and you would at least extend your range.
I never have been a big fan of electric bikes. once yer out of power yer sitting around for at least a couple hours waiting for the thing to charge. A gas bike, 2 or 4 stroke, you just dump in more gas and go. But there are a lot of people that swear by elec. bikes. I'm just not one of them.
All that said, it's up to you and you only bro. It's gonna be your bike so build it your way.
Big Red.