Welsh Grand National-winning trainer Thomas and Cheltenham Festival-winning owner Dai Walters were among five people involved in the accident on November 1.
The 76-year-old Walters suffered more serious injuries than the other passengers when the crash occurred in woodland near Llanelidan, Ruthin, Denbighshire. He needed CPR at the scene of the accident before being taken to Glan Clwyd Hospital.
The Hollies Stables handler reported that Walters, who also owns the yard, is "well on the road to recovery", but has his full attention on the three-day meeting which starts on Friday.
Thomas has a strong chance in the Paddy Power Gold Cup with Stolen Silver (13/2), who will be ridden by Sam Twiston-Davies.
"The horses are running fine, but I really don't want to talk about the incident. They are running fantastic," said Thomas.
"I'm fine - just keeping the show on the road. That is all we can all do. Just keep the horses in top form and keep kicking.
"They have been running out of their skins, so we are delighted. They are obviously happy and healthy and long may that continue."