I heavily use Sketchup and the workflow is more or less fine for me. If you’re importing walls, floors and ceilings then it’s pretty much a direct port over to Unreal Engine 4.5 and up (thanks to the imrpoved auto lightmap UV). If you’re using an older version you’ll have to resort to making a lightmap channel for your fbx file.
For more complex or more organic objects you’ll inevitably have to manually lightmap them. Half of the time you can get a away with just automatic flattening though.