New plan this is the blue print
From your description, I had a feeling it'd be a Treego-like front arrangement, as I recall you selling one a year or two ago. Looks a tricky construction. The last steel things I welded together was while making a junior hacksaw in school, many many moons ago - I still use it practically every day... the weld held. It has a blade tensioning screw, which I made too.
You sir have jostled a dozy minnow! I am now inspired to learn steel welding at any reasonable cost (under £20), using all of the resources I already have (about 12 butane gas cans) to convert a Homcom bike trailer to a fully enclosed tri wheeled e-car with rear single wheel steering, legally classed as a pedelec beause it'll have pedals and use a 250W rear hub... unless of course it's a terrible idea and everyone tells me so (it is, of course a terrible idea, so I won't do it - still, steel welding would be a useful skill to have, and one I'm envious of in others).