I am not comfortable with I fund because of Exchange Rate risk. YMMV.

I think you've got it backwards. Regardless, you shouldn't be market timing these types of things. If you want to stick to market cap, is around 50% international. It is a great diversifier, though not popular in the US due to home bias and recency bias.

If the dollar is strengthening, wouldn’t it be advisable to put funds in the I fund because a stronger dollar improves the profits of foreign companies?