Personally out of those I’m most interested in the road editor, and I think there’s a very easy way to get a “good enough” version of it: Feature request: delete “Take a break” entries
(Obviously infrastructure improvements should take priority over that if they threaten the stability / security / acceptable performance of the site.)
Re: endless backlogs vs. issue bankruptcy: I think endless backlogs are underrated. The issues you aren’t currently planning to do are still a place to record votes (by devs or users) and promote some of them. You do need to scrub them once in a while for things that have been made irrelevant (if A has been replaced by B, any improvements to A no longer apply).