because the American Funds allows no "B" share contributions when the account is above $100,000.00 in total value so why that is an issue is strange to me. Almost all, if not all, load funds cut you off at $100,000.00.
"C" shares are only appropriate for those with a short term horizon. "A"shares are definitely the way to go with a 20-year horizon.
With my clients I frequently use Short Term bond fund and then move the money to equity or bond funds. No time frame for a waiting period as one can do it the next day, next week, or next month. Saves client money--less for me--within IRA great way to dollar-cost average on a weekly basis.