hi made a little tutorial for creating internal structures supports for 3D printing models using meshmixer, is based on a Maker´s muse tutorial but what they had presented some problems I think I was able to adress better with this method, specially for hi poly and complex models, I leave here the link for the tutorial and for the model used in it ^^
This work well with hi poly mesh and does not increase the file size by much.
Meshmixer internal support structure tutorial
hope its usefull, please let me hear your comments