Rule of thumb for normal cars on a track day is to reduce the pressures as the heat in the tires will rise considerably more than standard use. For the 3 Wheeler you are probably right to just pump them up as the 3 wheeler is so light and doesn't really have enough lateral grip to create much heat. I'd just keep an eye on the rear if you go out for an extended session as Goodwood is both fast and quite rough tarmac. It's a PITA driving off the marbles you can create on the surface of the rubber if they get too hot.
I should probably just bite the bullet and come but am still suffering long journey paranoia after popping a spark lead on my last trip on the M25 and losing an engine bolt and spacer the time before.
