May I recommend:
DIY Electric Car Forums - Electric Vehicle Build and Conversion Community
I've been haunting the site for a few months, and i've gone from total ignorance to...er...knowing to ask the right questions, at least.
Make sure to check out the Wiki, located in the upper-right corner of the page-it's a treasure trove of free brain-candy!
The really basic questions need to be addressed first-how heavy do you estimate this Trike, and how many passengers/cargo do you envision for the load? How fast do you wish to go and how far? Delta(trike) or Tadpole(reverse-trike) configuration? And above all else, how much money do you have to play with?
Bear in mind that I haven't built my own EV yet (no funds, but i'm saving up!) so right now my Search-fu is all I have to offer...
Free Development Plans, Software and Information Trike plans (gas, EV and Hybrid) with free advice on Body Moldings and handling stats on Trike configurations.
3-wheelers.com MainPage A total love affair with all things Trike and an A-Z list of all 3-wheelers ever made commercially (with links to the active distributors)
http://solarvehicles.org/home.html Probably less power and range than you're shooting for-but the plans are free and can be scaled up...
EV Photo Album: Our Electric Cars on the Web Just to drool over-keeps me going while I save penny upon penny!
Best of luck.