Another suggestion is plotting "valence electron density", as described in my paper http://www.whxb.pku.edu.cn/EN/10.3866/PKU.WHXB201709252. You can easily use Multiwfn to plot this kind of map, see Section 4.6.2 of Multiwfn manual for example, what you need to do is setting occupation number of inner-core MOs to zero and then plot electron density map as usual.