Yep i use only SimLab (because it's very easy and permit to mix many 3D formats in the same time ) in free that is now 1920*800
or even SketchUp format! So no problem of regulate : you can play with smaller etc... if you have complex volume...

example with a model by thegoodguy
I have not made any special regulates (that was just for a test :)
Here SketchUp export from Moi : as you see you are not obliged to use OBJ format :)






A trick : export different objects against all in one if there are several complex objects!

You have another very cool free one (if you had loaded it previous year) : TwinMotion ! Without any limitation!
Updates are free too!