We are teasin' a bit.
The appropriateness of using SketchUp for this project is a valid issue.
SketchUp has an internal tolerance of 0.001" with respect to geometry vertices (and I think also guidepoint [aka cpoint] coordinates.)
So at 1meter = 1LY, vertices can be no closer than 0.0000254 of a meter/LY. (Ie, 25.4 micrometers/microLY.)
That translates to 240,301,780,000 m (2.403 x 10^11 m), or 1.606 AU, or ~13 lightminutes for the minimum vertex separation.
If that is fine, then okay.
On the high end, the galaxy would be 180,000m across. That is like a model 112 miles in diameter!
SketchUp wasn't designed for such large models. You may see display clipping issues the farther you get from the origin.