any advice on how to run the open 4 and open 8 in the same meet?

Ummmmmm....which event is first, and how much time do you have between events? Your race times won't matter to this advice.

Herbal tea bro

I should've mentioned that in the post; I just assumed it was the same in every state. The 400 is first, then 2 heats of both the boys and girls 300 hurdles, one heat of the girls 800, then the boys 800

Order usually goes ...400, 100, 800...

My advice is "sack up!"

Or get a few teammates who don't have any events after the 100 or aren't actually racing the 100 to intentionally but not so obviously false start. It might buy you a few minutes. It worked for my high school coach when it was in high school in the mid '70s.

I have the same problem as you, as I usually run the 400, 800, and 4x400.

My 400 time is the same as yours, but my 800 is around 2 seconds slower than yours.

My meets go 400 (my event), 300 hurdles, then the 800 (My next event), so there's only the 300 hurdles between them. It sounds bad but honestly so far it hasn't been. I do a .75-1 mile warm up before the 400 (I usually start the warmup 45-60 minutes before the start of the 400m), with a few quick strides (right before the race) and lots of stretching after you have warmed up.

Then after the 400 I only do a 1 lap (400m) cooldown/warmup, before the 800m. After the warmup, I take my spikes off temporarily (I don't put normal shoes on, I just stay in sox) and do some stretches on the grass. Usually there's only around 20 minutes before the events so there's not much time. Make sure to take a few sips of water (not too much) before the 800m. Once gain do 1 or 2 stride outs right before the race starts.

After the 800m do a 1/2 mile cooldown or so depending on how you feel. And stretch.

When stretching, I mainly do dynamic stretches, and a few quick static stretches.

Good luck