A guy could use a grinder and create a V notch between the hinge and the surface being welded and do a root pass and 2+ filler passes and still have good penetration. Yes, it will take a long time with that welder, but I have successfully welded engine mounts in offroad trucks (where it wouldn't matter as much as something on the road) with an 80 amp flux core welder. That repair lasted the 3 years I had it in the truck (before I shoehorned it into my mustang).
I do agree though. Do a bend test to make sure there is good penetration.
A more detailed description of what I suggested^ And if the thinner guage metal is prone to blowing through from the lack of adjustability of a cheaper machine its simple enough to bias your arc to the thicker piece and only move the pool to the thin guage long enough to fuse the two.
Not saying it can't be done, just most people with a 80 amp welder has no clue how to weld...If it sticks together they think it's welded good.
Most people dont know how to weld period! And a fancy machine dosnt help at all imo.
When I was tought to weld I had the "opportunity" to use many poor welding machines including some antiques in dubious states of repair that the instructors claimed were used in ship yards circa WWII.
Learning your way around fiddly adjustments and wildly unstable arcs can definitely hone your attention to the finer points of the craft and allow you to step up to a quality machine in time and knock out some really great works with an artistry most younger welders lack.
In the case of the OPs scenario though the ability of the machine to weld heavy materiald is a moot point, his real issue will be reducing the output enough and stabilizing the arc enough to get quality welds in the lower range.
As for my own work, regardless of the machine being used I dont fool around with attaching critical parts. I utilize every possible "aid" to stregnthen the item possible with bevels fish mouths plug welds and arangint the attachment points so that I have the most possible continuous bead.
Im a little anal about it actualy, one of my projects this year is to remove both subframes from my car and follow up the factory sections of weld (maybe 1-2" each with several inches un welded seam between) so the parts are completely solid. Before I repaint it I'll be doubling or trippling the seam spot welds and adding select gusseting and aditional seam welds throughout the chassis.
All using little more than my humble warmed over HF 120 and a HF spot welder