A practical note
Sadhugram exists only when the Kumbh is on. The Nashik–Trimbak Simhastha runs roughly every twelve years (the last was in 2015; the next is anticipated around 2027), so outside those windows you will find the Tapovan grounds as open riverside land rather than the tented city. Plan a visit around the mela calendar, arrive early on bathing days, and treat it as a place of pilgrimage first and sightseeing second.