You do not need a "very specific trust." There are several straightforward ways to acquire flexibility over the way assets are distributed in a marital estate (either upon death or divorce). Furthermore, community property jurisdictions, like Colorado, recognize the existence of “separate property.” Separate property is property that a spouse owned before the marriage or that the spouse received as a gift during the marriage. And separate property does not become part of the marital estate simply because it is acquired during the marriage (even after 50 years of marriage).
Indiana, however, applies the principle of equitable distribution; it is not a community property jurisdiction. And it is also important to keep in mind that death and divorce are not the same (though I hear divorce can be as bad or worse than death).