I know what bike you're talking about.
Here's mine. A worksman Trike with 20 inch wheels.
http://motorbicycling.com/f15/lfs-trike-powered-titan-front-wheel-4046.html
The advantages to having it front wheel drive is that there's no pedal chain to worry about here so it doesn't matter which side your drive sprocket on your wheel is on and you can keep your basket in back. I love my Titan setup and you can rather easily mount a 44 tooth spoke sprocket up front and your good to go.
On mine I adapted a 5 speed hub so I have perfect sprocket alignment and a freewheel. Then I changed the jackshaft sprocket from the stock 10 tooth to a 12 tooth and that made my gearing happen considering my drive sprocket is a 28 tooth but the 20 inch wheel makes up for it.
In about a month I'm gonna be fishing for a 3 speed wheel. Then gear up the jackshaft sprocket so it would gear nice with the wheel's stock 20 tooth sprocket.
If you have a welder and want to go even cheaper get a China girl and adapt a front rack for it. Drive the chain straight down to a 44 tooth spoke sprocket.
Yea,for a bike like that,Front wheel drive in my opinion is the way to go.