I’ve found a solution which works great. I ended up copying the bbPress Reply Walker class which was an extension of the WordPress walker class, and modifying some of the parameters to meet my needs. I had to also make my own function for listing replies, similar to bbPress’s list replies function. The list replies function had custom args as follows:
$args = array(
'post_type' => 'reply',
'post_parent' => $postID,
'posts_per_page' => 50,
'orderby' => 'date',
'order' => 'ASC',
'hierarchical' => true,
'ignore_sticky_posts' => true,
)