Couldn’t find anything when searching online so thought someone might need to hear this - you can actually run the ue4 editor in HDR if you have an HDR monitor (thanks for the tip Jack Knobel!). Definitely does live up to it’s categorisation as ‘experimental’ though haha.
It doesn’t appear to be a complete 1:1 representation of what you’re going to get in a packaged game. UI for example doesn’t respond at all to composite mode commands), but it’s definitely better than having to tune lighting completely blind.
It’s in Experimental Editor Preferences. Of course. Tick the box. You know you wanna.