The model you have here looks to be a model that you would use for production. It is not often that a model used for production would translate smoothly into FEA. The main issue in your model is that it has not been simplified from a production model into an FEA friendly model. Specifically, the trim features you have applied to each structural member are not necessary and actually making it more difficult for the program to calculate the neutral axis of these structural members for use with beam mesh. So, first think would be to suppress all the trim features and allow the bodies to overlap (this is one of the few cases in FEA where this will be a good idea). Likewise, you will want to edit features like "Front V Support" to turn off the option for "Apply Corner Treatment" for the same untrimmed effect.
Next, you have a few structural member definitions that are pieces of bent tubing (i.e. the feature named "Front Roll Hoop") where the straight segments of the member and the arc bends of the member are being generated as disjoint bodies. This will make beam members that are too short to be considered appropriate for using beam mesh. You would want to edit all these structural member features to enable the option for "Merge arc segment bodies" so it turns into one large bent piece.
After doing all this you have a model that will mesh using beam elements:
Now, if you are going to use solid mesh elements (right clicking each beam body in the study tree and applying "Treat Beam as Solid" to them) all of this advice goes out the window and would be replaced by a meshing method like this (GoEngineer - Simulation: Using Mesh Controls to Solve Mesh Failures).
Thanks so much! This worked perfectly