Hi Becca! I've done LHTH and LHFHG twice now, and I am very sure that you can do them both without a problem. I've subbed in things myself off and on, just based on my son's likes and dislikes. There are usually always several choices for food type things to use in the plans anyway, so I think that would totally work. Also, we did LHTH much more quickly when I used it to teach children whose moms were attending a Bible study once a week. One idea I had for you is to do one day of plans in the morning, and one day of plans in the afternoon. We finished up that way with one of my sons when summer was approaching, and we wanted to finished by Memorial Day. It worked out just fine for us! HTH, and prayers for your ds and his allergies! So glad you know what it is and what to do about it!
Blessings,
Julie