@DaveR is correct that annotations such as dimensions are more powerful and easier to handle in Layout. If your model has a complex background that must be visible, that may be the only way to cope, as SketchUp’s dimensions do not have any setting to make their bounding box opaque.
I would point out, however, that fancy stuff such as a background image is usually not needed or appropriate in a view whose purpose is to show dimensions. Also, objects that are not being dimensioned may be clutter that doesn’t need to be shown unless it provides essential context.
If you have only Make or prefer to create them in SketchUp despite having Pro, I recommend the following workflow:
- Do not add annotations or dimensions until the model is essentially complete. Anything you add later is at risk of the sort of collisions you mentioned.
- Create a scene for showing dimensions, then orbit, pan, and zoom until you have it the way you want. Associate entities that are not essential to the dimensioning with layers that are not visible on the scene so that they avoid the clutter per your original quesiton. Update the scene to remember the orientation and visibility. Depending on the use you will make of the dimensioned model, you might also want to set Parallel projection and one of the standard view directions.
- Add dimensions, fine-tuning the scene’ view as necessary.
- Create a new layer to contain your dimensions. You want this layer to be visible only on the current scene. There are various layer management extensions that facilitate this. My Dimension Management Tools extension (available from the sketchUcation extension store) includes a Tool to select all the dimensions in a view and associate them with either an existing layer or a new layer that is visible only on the current scene.
- Update the scene before changing to another!