Charlene,
I'm another one who has a 3rd grade boy in Bigger this year.

For us, the writing hasn't seemed too overwhelming because it is dispersed through the subject areas well so that we don't have a really heavy writing day.
A couple of things that we did that I don't see mentioned here are...
We skipped the copywork of poetry for quite a while (like 10 weeks or so). My ds is new to cursive this year so we're doing Cheerful Cursive this year. Once we got into the guide a ways we added copywork of 2 lines from the poem per day. (We rarely finish the poem. An idea from a mom here...I never would have considered "not finishing" as an option.

) You could skip the copywork all year though if you're doing Cheerful Cursive. It's listed as "optional".
The vocabulary cards seemed especially overwhelming to my son at first. Here's our "plan" that I shared on a week-in-review in October.
We did vocabulary on Monday which he has grown into so well. I know I saw several moms that also had the problem of this part of the guide being VERY time-consuming as they started the guide, so I'll share how we're doing it now. I have Grant find the 1st word in the book, guess what it means, look it up, I write the definition, he dictates a sentence to me. We repeat this for the 2nd word. Then for the 3rd word, I listen to him find it in the book and guess what it means, and then leave him to finish it on his own. He draws pictures for all 3. This has given him the practice of finding the words in the dictionary more quickly - without the writing being too much for him. At first I had tried going through it together and having it on a white board for him to copy, but this didn't work well for us. We like our method now!
We still follow this plan and it's going great! It seems to be just right for us. I have occasionally had him do 2 of the words independently. (This was actually when he wasn't quick in coming downstairs from our history reading...daydreaming his way down. I was sitting there waiting to help him. I was planning to follow the usual plan but because he had wasted the time I set aside for it, I couldn't skip my other jobs for the day.)
Hope this helps some!

Kathleen