john61ct said:
and is suitable for rough cross country use, desert tracks, dirt/gravel roads and BLM / forestry trails
At the least, you're gonna want much larger diameter rear wheels than that thing, preferably with fat wide tires, for that kind of terrain. You'll also want a much lower deck, because that is so high off the ground you'll end up at only a few MPH most of the time just so you don't tip while dodging road debris or holes, or making turns, etc.
Most likely, you're going to want motorcycle wheels and tires, as large a diameter as you can get, for the best ride quality you can get without full suspension, independent on each wheel.
For the larger wheels, youll either have to have a wider track, or a narrower cargo deck at least where the wheels are, and suspend the deck below the axles like my brother's Raine Trike and my best and biggest trailer.
I'd highly recommend good suspension for that kind of terrain, too, or you're gonna end up riding at walking speed or less so you don't bounce your load or brains out.
As for a trike design that can haul heavy loads, there are lots of those, including my SB Cruiser and the Raine Trike I built for my brother. Either one of those designs could be modified for good suspension, though I'd use the suspended-deck Raine Trike design for the much larger wheels it can have, without having such a high deck. SB Cruiser uses smaller wheels to keep the deck lower since it's axles are below the deck, but it rides significantly worse than the Raine Trike over the same poorly maintained streets, even though the tires are much fatter.
There is also the CycleTruck that various companies, including UPS, are using. It's probably overkill for your hauling capability needs, but it might have the power to haul up the hills you're talking about. It doesn't have the suspension you need for the terrain you're needing to deal with, though. (nothing presently existing does, that can haul the cargo you need to).
john61ct said:
carry a 200lb load over a 2000m mountain pass in the rockies or alps, given a big enough Ah capacity bank of high-discharge rate batteries
I don't know how much power you'll need to haul up those mountains, without knowing the speeds at which you need to do it and the actual slopes. Probably at least several thousand watts, continuous. It's not much of a cargo load, but the trike itself will probably weigh at least twice the load, plus a rider....
That will determine how much battery you need, whcih I expect is going to be so much that it will be greater than your cargo load mass. A few dozen kWh, probably. (because the more mass you add, the more power and thus the more battery you need to move it uphill)
I think this is going to be a pretty expensive cargo trike.
