Hello Ryan,

Midsurfaces are the right way to go.

2) Don't worry about gaps between tubes. These can be connected using Mesh Connections in Meshing, or can be connected using Bonded Contact if the Mesh Connection doesn't work well.

1) Did you know SolidWorks has a Midsurface feature?  Try that as well as the SpaceClaim tool. For a member that will not midsurface, in SW, remove any operation that attempted to unite the two tubes.  Simply use one tube to trim the other tube to the correct end profile without uniting it.  Two separate tubes are much more likely to successfully midsurface than a complex united network of tubes.

SpaceClaim will onlyl make midsufaces of tubes that have the same wall thickness. If you have two different wall thickness tubes, they have to be created in separate midsurface operations.

Try saving your 3D sketch as an IGES file and opening that in SpaceClaim.