I am rambling and may go off topic, but....
My kids are 4 years apart.
It was not planned this way... it just so happened.
BUT, I LOVE IT!
My kids, though being 4 years apart, are very close, like 2 peas in a pod.
Age spacing, has no bearing on if siblings will get along or not.
I have a sibling who is close in age to mine... but we never got along. UGH!
And with more kids, your Husband WILL need to help, with taking your kids to places, TOO.
It just is.
Now, once I had 2 kids, and my son was still a newborn and baby and Toddler, his naps.... were as it was. I did not schedule anything else, at those times. AND he was not a portable napper. Meaning, he would nap ONLY at home. He could not and would not nap, on the go or in the car or in a stroller. AND when he was born, BOTH my kids, had the SAME nap times. My son as a baby, napped 3 times a day for the first year. My daughter would nap during his afternoon nap time. For example.
The 2nd year, my son would nap twice a day.
The 3rd year, he'd nap once a day. Afternoons, by then.
Then he'd still nap, even while in Kindergarten.
He was a napper, and VERY regular about it, no battles.
My daughter, too.
If you can, make naps at the same time. I did with both my kids, until they outgrew it. Then at that time, my older one, my daughter, would UNDERSTAND that, though she outgrew naps, her brother STILL napped... so the afternoons were QUIET time. Whispering, time. And it was fine. It was, routine. EVERYDAY.
Per young kids and scheduling conflicts.... I just went according to my kids' naps, at that age. Because, without naps... my kids were GRUMPY fussy Trolls, by late afternoon. And if they did not nap... they then were OVERtired by their actual bedtime, and being overtired meant, they did NOT go to sleep well or fall asleep well at night. It backfires... when a kid is overtired and can't nap.
Being young like that (5), they do not have to... be in sports or activities. Yet. A child is typically in school too, at 5 years old. So they already have a full day. And that in itself tires them out... being at "work" at school all day.
My son didn't start sports/activities/extracurricular activities until 1st grade. For example. And it was then, that he wanted to.
Or, you might have to hire help. So you can, take your eldest to his sports things. Instead of, taking all 3, with you.
I have seen some Moms do that.
I have also seen some Moms that tote all their kids (baby included) to their one child's sports activity... and then, they are kinda going bonkers. Because, the other 2 kids are restless/tired/a baby, and its hard keeping eyes and ears on all of them, while "waiting" at the sports lesson, for the other child.