Combine the stasis with a magically induced neuromuscular electrical stimulation.
This is a potential method to protect people in cryostasis from atrophy during long-distance space flights. This article mentioning it is an interesting read in this context altogether.
Another problem youryou're facing is that of nutrition, and the general biological functions of the body.
The best option might be to induce a mind-numbing zombie-like state, in which these husks have been instructed to follow a simple predetermined daily pattern of exercise, eating, and sleeping.
Their original personality might have been completely 'wiped out', and their consciousness suppressed sufficiently, so no sudden surge of existential anxiety or similar unwanted reflective behaviour occurs - mostly to prevent psychosomatic or self-inflicted damage.