I'll be honest, it just seems like a bad idea to me.
I've got my Worksman front-loading tricycle, and have put a few miles on it. But one thing I notice is that having 3 wheels does not eliminate the need for balance and handling ability. Yes, if you stay on flat land and go very slowly, no problem. If you're riding at anything beyond a crawl, it's easier to turn a high 3-wheeler over than it is a bicycle. With the bicycle, you lean to compensate for the turn, and with the 3-wheeler, that is awkward to do- you tend to stay flat until it's too late.
It seems to me that the training-wheel solution would have similar problems, perhaps worse. For one thing, the weight is not all on the training wheels, so it looks like it'll let you flop from side to side some, with the amount depending on your weight and how flat the ground is. If you lean into a turn like a normal bike, you don't need the training wheels. If you don't, you're fairly likely to fall over the opposite direction.
Anyway, if it was me, I'd look into the lightfoot trikes, which share some layout similarities with the Worksman trike, but have a wider range of gearing.
http://lightfootcycles.com/products-...dels-overview/
I'm sure they're more expensive, too. If it's something you actually plan to use, it'll be worth it.