looking good since you have alot of room in the back you could try using a multiple gears setup in the back. You can use a front derailer and have smaller sprockets in the back, like a 44t,36t,27t setup you would have power and speed. Just an idea the concept would work if it was setup right.
O the spacing of the sprockets would have to be the same as a from sprocket setup and order.
Curious, did you fab up the rear, or didja use 1 a them trike conversion kits? My next build is gonna be a trike as well, using an OCC platform, n I don't think that the conversion kit is gonna work on the OCC frame due to the wider rear tire cage, so I figure I will probably hafta fab it up myself! Nice work dude! what's the top speed? Any idea? I'll be shootin for a 40mph+ trike myself, will c what I can do!