Trailing white spaces are truncated by the browser as calling get_html(true) triggers DOM operation over the content. However, I can only make guesses how the truncated white spaces can cause issues.
There is no configurable option to prevent truncated white spaces and remove the BR tag. Mostly because the two behaviors are not related.
Therefore, you can continue using get_html() and additionally use Regex (or other option) to strip teh last BR tag.
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