Ultimately, the governing standard to guide the Board of Trustees' deliberations in passing on the merits of such applications shall be the protection of the public's health, safety, welfare and morals. Where it may be shown that a proposed religious or educational use will sufficiently detract from the public's health, safety, welfare or morals, an application for a special use to establish or expand the institution may properly be denied by the Board. In less adverse cases, appropriate restrictions may be imposed in the form of conditions to be attached to the grant of a special use, limiting either the extent of the religious or educational use itself, or the nature and/or extent of its proposed accessory uses, if any. In any event, such conditions shall be reasonably drawn to counteract the deleterious effects on the public's welfare, but not, by their cost, magnitude or volume, operate indirectly to exclude the religious or educational use altogether.