Yeah, you can definitely get all the spouses to dance with you at the first dance. I don't have time to do the math now, but
this thread on the old forum and
this reddit post have a detailed breakdown of how to do it. (Not sure what it says about my priorities that I remembered a forum thread about this from 2019. Why can't I apply this sort of memory to stuff like where I left my keys? :P )
Basically, you can get mostly gold-quality liked gifts for all of the candidates, even if you can't get loved gifts, because vegetables are a universal like so you can just plant a bunch of parsnips. Gold quality parsnips plus a couple silver parsnips from week 1 plus talking every day isn't quite enough, but you can usually get a couple extra either from a dialogue option in a heart event or by switching one out for a loved gift that's available in Spring. (Also you can talk to them at the egg festival now, which helps.)
For the three who hate all vegetables (Abigail, Haley, and Sam):
- Haley likes daffodils. It might be harder to get her gold-quality daffodils consistently, but giving her one on her birthday makes things pretty simple.
- Quartz, salad, or flowers are all liked gifts for Abigail, but unless you plant a lot of flowers (unfortunately more expensive than parsnips) you probably can't consistently get gold quality. But she does love amethysts which you can get in the early levels of the mines, so you can make up friendship points by getting a few of those.
- For Sam, you can go with any other liked gift (e.g. Joja Cola, which is reasonably cheap) and make up the deficit from not having it be gold quality by buying him a pizza or two, which he loves.
Also, if you happen to get a "Help Wanted" quest from the bachelor(ette) you want, that gives a whole 150 points which obviously adds a lot of leeway. You can only get Help Wanted quests from people you've met (although unfortunately you can get mining and fishing quests even if you haven't met Clint or Willy). So it might help if you avoid meeting other people until after the dance. On the other hand, the vegetable strategy from the Reddit post assumes you get the 100 points from meeting everyone. YMMV.
Also
@BlaDe has a strategy for manipulating RNG to force billboard quests to appear - apparently you can manipulate it by changing the number of recipes you know?
EDIT: One other note, on the morning of the flower dance, you can enter the forest if you get to it before 6:10 am. Not sure if that's possible from the main house (probably not), but you can get Robin to build a cabin close to the south exit of the farm and sleep there the night before. This lets you speak with Shane and/or Leah on the morning of the flower dance for a few extra points. You probably won't need those points, though, since Shane is super easy and Leah has a buyable loved gift, so it's likely not worth the hassle.