Hi Steve and welcome to great cycling.
I am 5 11 and 85kg and enjoy my triking in Oz.

Things to think about,
Get a rack and any set of standard panniers to carry your gear in. I
find a a rack top saddle bag great for the day trips and panniers fine
for work or touring. The Greenspeed rack is excellent.
Most 1.5 litre hydration back packs can be fitted behind the seat for
water or you can buy the recommended Fastback unit if you want to
spend that much.
Wheel alignment is important to get right with your weight on the
trike. Poor alignment leads to poor tyre wear and lower speed.
Greenspeed Scorcher slicks are excelent tyres. I manage to get about
4000km out of a tyre, front or rear.
Remember to release the hand brakes!!! A lot harder to ride if you
forget but the handbrakes are a great feature of the Greenspeed trikes.
Water bottle holder can double to hold a small camera bag on top
without interferring with riding.
Kids think trikes are cool adults think trikes are weird. trike riders
love trikes and riding them.
Sliding around wet corners can be great fun but don't tell the kids.
Folding the GT3 is easy and quick. It fits in the back of most
hatchbacks and is done in less than 2 minutes. A smaller package can
be made by removing the front wheels as well (one screw each)
I have covered 500km per month over the last year so have covered a
few places including both road and trails, I have topped at 63km/hour
(on dirt road) and talked to one rider who has done 75km/hour. Trikes
are very stable at high speed and comfortable at all speeds. My
touring road average is about 35km/hour, Rail trail average with
trailer and fully loaded was 16 km/hour. Top average for road ride
over 1 hour has been 31.5km/hour. You may need to do the conversions
as I have forgotten imperial speeds.
In all GT3 are an great trike and good fun to ride as well but expect
people to look twice and think you are strange.

Mark