Of the $5mil allotment provided to invest in Bonds, I would diversify the dollars between Three Bond funds. They offer both internal diversity, an extended track record of more than 10 years, and low expense ratios. I studied their effective durations to find the highest yield to maturity with the shortest duration time closest to a five year average.
The first is the I share Core US Aggregate Bond ETF $2,225,000 (AGG)
The second is the I Shares I Boxx $ High Yield Corporate Bond ETF $2,225,000 (HYG)
The Third is the I Share Core US Credit Bond ETS $500,000 (CRED)
Source:
https://www.ishares.com/us/products/product-list?cid=ppc:ishares_us:google:Corporate-Bond-Rate&gclid=CIPE0YT7hMYCFQmPaQodULgAYg#categoryId=13&lvl2=yields