@wcarlsonM2NUS -
the overall idea is to break it up into a series of 4 sided lofts that are easy for fusion to handle, and create a patch from surface edges that are also easy for fusion to handle.
sketch 1 lays out basic location of then ends of the pipes.
sketches 2,3,4 each have a circle used to set pipe diameter and to extrude the initial pipe ends from.
these sketches also have a 4 sided polygon inside the circles used to split the pipe ends into 4 segments. these are the segments used for the lofts. I left the lines for the polygon free to move so I could drag them around after lofting to tweak the loft visually for better surface quality.
loft 3 needed a little extra help to get a good shape, so sketch 5 was used for a rail.
the relative geometry of the edges from the lofts (and the original extrudes) creates a boundary that can produce a decent patch.
If your interested in learning and understanding the approach, I would suggest studying each feature in the timeline. when you come across something you don't get, come back and ask questions.