These are a really good affordable option. They’re not the most pigmented but definitely will not bleed through.

Bic Corporation MSEAP81 0.7 mm. Cristal Xtra Precision Fine Stic Ballpoint Pen, Assorted (Original Version) https://www.amazon.com/dp/B01FWI7M0U/ref=cm_sw_r_cp_api_i_cXUJDb5NYYX08