Add text just before the closing tag using Nokogiri

I'm using a Nokogiri based helper to truncate text without breaking HTML
tags.

require "rubygems"
require "nokogiri"

module TextHelper

  def truncate_html(text, max_length, ellipsis = "...")
    ellipsis_length = ellipsis.length
    doc = Nokogiri::HTML::DocumentFragment.parse text
    content_length = doc.inner_text.length
    actual_length = max_length - ellipsis_length
    content_length > actual_length ?
doc.truncate(actual_length).inner_html + ellipsis : text.to_s
  end

end

module NokogiriTruncator
  module NodeWithChildren
    def truncate(max_length)
      return self if inner_text.length <= max_length
      truncated_node = self.dup
      truncated_node.children.remove

      self.children.each do |node|
        remaining_length = max_length - truncated_node.inner_text.length
        break if remaining_length <= 0
        truncated_node.add_child node.truncate(remaining_length)
      end
      truncated_node
    end
  end

  module TextNode
    def truncate(max_length)
      Nokogiri::XML::Text.new(content[0..(max_length - 1)], parent)
    end
  end

end

Nokogiri::HTML::DocumentFragment.send(:include,
NokogiriTruncator::NodeWithChildren)
Nokogiri::XML::Element.send(:include,
NokogiriTruncator::NodeWithChildren)
Nokogiri::XML::Text.send(:include, NokogiriTruncator::TextNode)
On the line content_length > actual_length ?
doc.truncate(actual_length).inner_html + ellipsis : text.to_s it appends
the ellipse just after the last tag.

On my view I call <%= truncate_html(news.parsed_body, 700, "... Read
more.").html_safe %>

The issue is that the text that is being parsed is wrapped in <p></p>
tags, causing the view to break.

"Lorem Ipsum</p>
... Read More"
So I'd like to ask if anyone knows how to append the ellipse just before
the last closing </p> tag using Nokogiri, so the final output turns

"Loren Ipsum... Read More</p>