A 52-year-old woman with rheumatoid arthritis and severe cervical spine involvement (C3–C4 fusion) is scheduled for elective hysterectomy. Preoperative assessment reveals limited neck extension, Mallampati III, and thyromental distance of 5 cm. Anesthesia is induced with propofol and succinylcholine. After loss of consciousness, the anesthesiologist attempts direct laryngoscopy but visualizes only the epiglottis (Cormack–Lehane Grade III). Bag-mask ventilation is successful. What is the most appropriate next step?