niceperson709 has weighed in on this (thanks), but I'd like additional input (perhaps from folks who don't usually peruse the three-wheeled section of this forum).

Here's the URL of the thread:http://locostbuilders.co.uk/viewthread.php?tid=22601

It's more work and joints but could you make a triangle with a bit more of your trailing arm material. It might load the front pickup point where they join to the bike though.
Rescued attachment trikeaxle.jpg