Price range really is part of the answer to this question. There are many different trikes that will and can do what you want. I am a trike rider, I own a TerraTrike (TT) Rover - which if modified could do what you want, but is best known as the SUV of trikes. It is a base-type model with few frills, 400lb weight limit, and 18.5" high seat, and relaxed riding position - great for new trikers.
UTT - Utah trikes
http://www.utahtrikes.com/ is your best single website to learn about most all popular models of trikes. They are also *the* custom shop for TT. They are one of the largest seller's of trikes in North America.
I do not know if you have ridden a trike yet or not. A few basic guidelines if I may?
Trikes really are slower than bikes - call it why however you want, weight, 3 wheels, whatever, but most folks are 2-3mph slower on a trike. As you stated, speed is not your critical factor, so this is a non-issue. What IS nice about trikes, what they are known for - - all day comfort! Seriously~! I can do 8hr rides day-after-day on mine. Can really haul a load without feeling it. Can go as slow as you like up a hill, AND, be relaxed at the same time, whenever you stop, there's your chair
Pulling a trailer only means slower up hills.
Shoot for a low gear between 10-14GI (Gear Inch) - use Sheldon's wonderful site to figure gearing
http://www.sheldonbrown.com/gears/
Suspension vs non-suspension - a $1000 buck question~!? Some love it, and swear by it, and others could care less. Or, get "Big Apple" tires (poor man's suspension) 20X2.00 - great comfortable tire, not slow, very fl@t resistant, change tire pressure to adjust ride comfort - sweet~!
My every-day ride includes me and 40lbs worth of crap - I am a pack-rat. I weigh in at 325lbs, so me, trike, gear comes out at roughly425lbs going down the path. I built a Wike DIY trailer that I haul 80lbs of dog chow often. My Rover is an 8-speed with a bottom gear of 14.9GI.
Cheapest around $1500 all set-up, upwards to $4.5K easily - so, what do you want?
The new GreenSpeed (the father of all trikes) Magnum is out FEB 2012, base price is 3K, has a 400lb weight limit, and GreenSpeed makes *THE* best Touring trikes period.
ICE, HP, TT, Catrike are you other best choices for brands. TT has lifetime waranty, US made in MI, and is sorta the budget trike company. Wonderful customer service~! The New 'Rambler" just started shipping~! 325lbs weight limit, lots of gear choices, lots of MODs by UTT.
Here is your start
