VegasTriker

It is also a matter of availability. If you search all CL for the Greenspeed Anura, only one shows up nationwide located in the Portland OR area. It was listed for $1,800 but dropped to $1,600 after not selling for about two weeks. A different search shows one available somewhere in SoCal for $1900. Greenspeed makes great trikes but was not up there is the top tier of how many were manufactured since it was pretty much a one man operation under the late Ian Sims. That means not a large selection on the used trike market.

There are only two trikes that I can find that list a maximum weight above 300 pounds. Remember the OP wishes to carry groceries so if you add that to his weight you are really pushing the limit for trikes rated at 300 pounds. While the Sun trikes are not great when it comes to weight and not the same quality as the GS trike, they are far more available on the used trike market . I'm not fan of overweight trikes but you get what you can find in your price range.

Greenspeed Anura - trike weight 39 pounds, weight limit 300 pounds MSRP varied from about $3K to $3.5K depending upon components
Sun Eco Tad - trike weight 46 pounds weight limit 300 pounds
The only trikes I see with weight limits over 300 pounds (both at 400 pounds) are the Trident Titan at 44 pounds and the Sun EZ3-USX at 65 pounds

I've seen the Sun trikes come up for sale on our local CL once in a while. It can be sourced by any bike shop even if they don't deal in recumbent which may be the reason it shows up more often than other brands.

I don't know what trike paths are like other than where I live and in the San Diego area but I can't recall any bike path I have encountered in either of those places that wasn't suitable for my recumbent trikes. They are certainly as wide and at 7 feet long, probably as long as anything the OP would buy.