Guava and Lychee should behave like citrus plants do in your area. Tip and new growth damage will occur but as you will be pruning and shaping after winter you can cut out the winter damage. Snow is alright it is this ice storm which I am not familiar with. What on earth is an Ice storm
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Anyway whatever, you will have to plant them right now so their roots get maximum time to get established before next winter. Also you will have to see them through the first winter, after that they can be left to their own devices. Lychee has been well studied in the U.S and if you make a net search you will find the relevant data for your area.
For winter protection take three sticks and tie the tops together, put over plant then cover with bubble film like a wigwam or you can use straw if you consider your winter to be harsh. Plastic does not give of heat of decomposition while straw does.
Regards,
Arif.