I found a way with Microsoft ALT codes that works for the website. I will try to demonstrate here in the forum. Even if the special characters show up in this editor, they may not show in the submitted post. That’s what happens on the website — the indents show in the Editor but not on the live page. Proper indentation is very important.
By entering ALT 0160 Non-Breaking Space seven times in a row, I can indent this line. It shows in the Editor. If I enter ALT 21, I get this character: §. ALT 0137 makes ‰, ALT 0134 makes ?. With ALT 138 and ALT 130, you can even spell resume like rèsumé! Even though the ALT 09 Horizontal Tab does not show on the live page, I will enter it here to see if it shows in forum posts. It does not. But the nonbreaking spaces will work for indenting. And you can use two Non-Breaking Spaces after periods so HTML won’t cram your sentences together.
You don’t need the Rich Text Keyboard Input feature to enter the ALT codes, but if you use it, the special characters display in a different style than the ones without it. Can’t demonstrate that here though; it’s not in the drop-down,
To enter Microsoft ALT codes, you press and hold the left ALT key, enter the decimal code on the numeric keypad, release the left ALT key. All you need is to find a table of the numeric codes and if necessary convert the Hex values to decimal. There is a nuance, however. There are two different bases for the key codes. Codes with a leading zero like ALT 0160 yield a different character than codes without a leading zero. So ALT 0160 is Non-Breaking Space, but ALT 160 is á. The base with the leading zeros contains the control characters.
The best ALT codes table I found is at altcodeunicode.com.