Actually in the interest of time I made a new scene showing only this part and selected the standard Left view in LO. It could have been done with the scene you were using. If you did that, the key would be to avoid double clicking into the viewport to pan, orbit or zoom. If you must use that scene (LO | TRUSS BB) to show K1, you can do that but instead of double clicking the viewport, just drag the edges of it to show the component of interest. To avoid creating problems with link between the model and the viewports it is best to avoid doing anything that results in the scene showing as modified in LO.
You have your model spread out over a fairly large area in the model space. That distance can create problems, too. If I were going to do something like what I see in your model, I would do a few things differently. First, I’d give each of those components a useful name to make it easier to identify. Then I would give each one a layer/tag and I would have them stacked in essentially the same place within the model space. Then each one would get a scene. This can be very quick to set up because you should be able to use the same camera position for all of the scenes and just change which component is visible for each scene.
Then in LO, you can set up the first viewport showing the first truss of interest. Set its scale as desired in the SketchUp Model panel and maybe drag the edges of the viewport to show the whole truss if you need to. Move the viewports on the page the way you want it. Maybe that’s centered both horizontally and vertically. After that first viewport is set up, duplicate the page, change the scene to the next truss, rinse and repeat until you have all of the trusses represented.
If you do the same sorts of truss drawings and use the same scene names all the time, you could create a SketchUp template with those scenes already set up. And then you could create a template that is already set up with the viewports linked to the scenes in your SU template. After that you only need to select your new project’s SketchUp model as the reference in LO and those viewports will automatically show the trusses. You’ll only need to dimension them afterward.
BTW, you should make sure you are using Layers/Tags correctly. All edges and faces should be left with Layer 0/Untagged assigned to them. I fixed your model.
It’s also a good idea to purge unused stuff once in awhile. Otherwise your file can get bloated.