Here’s a product that might work for you. I use a similar model. You might be able to do better, but this one is a solid choice. Its rechargeable, had an attachment for hard to reach areas, and its pretty hard to cut yourself, even on sensitive and uneven areas.
$40 US: Philips Norelco Bodygroom Series 3500, Showerproof Body Hair Trimmer for Men with Back Attachment, BG5025/49 https://www.amazon.com/dp/B078G9BKBW/ref=cm_sw_r_cp_api_i_RvcmFbDE80WT2