Combining SCM Early Modern & Modern for American History only?

We have been doing a four-year history cycle using SOTW, but I don’t see volume 4 working for us for next year. One of the things I’m considering is doing a year of just American history. I’ve looked at a number of different resources, but I really like the structure and the lighter schedule of SCM, the incorporated geography and Bible, and the ability to keep the schedule flexible and take rabbit trails off onto subjects that interest us.

My question is, has anyone tried using just the American History parts of Early Modern and Modern in a year? It works out to schedule it, along with North American geography, coming out to 178 lessons…but not having used the curriculum (and with only samples to look at), I’m not sure whether we’d be missing out on crucial context by omitting the world history parts. Any thoughts?

Note: I will have a 4th and a 2nd grader this coming year. We’d probably supplement their individual reading time with more books from the Sonlight or TruthQuest lists, because they are both book junkies.