Merge mesh proxie generator. Standalone? Alternative?

Hi, im working with getting cad models into unreal. This yellow part in the images attached contains the insides of the metal beams aswell as the outsides. Thus making twice as many polygons as nessesary. The “proxy maker” under developer tools is the closes tool ive encountered that optimises this mesh for me, deletes hidden faces and reduces amount of polygons. But 1200 wich is max “resolution” is a bit low, and also it looks like crap if you take the generated proxy mesh into substance painter or 3ds Max. Does anyone have a similar algorith or function in another software that does this?