Welcome to the IBA UK and good luck in your challenge.
If you haven't already you may want to read
https://ironbutt.org/25tips.html its aimed at the USA 11 day IBA Rally but you'll get ideas for a one day 1,000 miler.
May be come along to a Ride to Eat (RTE)
https://forum.ironbutt.org/index.php?forums/uk-rides-to-eat.90/ and ask away, we're a very friendly lot.