Good enough to place in a New Zealand and Victoria Cup, he is a natural stayer well suited to the rigours of Cup racing.
However, when you have stablemates named Auckland Reactor and Sushi Sushi, you start the season a fair way down the pecking order.
Yet Sleepy Tripp's workout win on Monday suggests that could all be about to change.
He sat parked for the last 900m to beat Mah Sish and stablemate Major Mark, with Auckland Reactor, Highview Tommy and Sushi Sushi further back but not pushed. Purdon says the win convinced him Sleepy Tripp could return with a win in Sunday's Hannon Memorial at Oamaru.
"I have been pleased with both his trials and he has reminded us all what a good horse he is," said Purdon.
"Initially, I thought Major Mark, who has been gelded, was the most forward of my open-class pacers but after that I am not so sure.
"I'd say Sleepy Tripp now has to be our best chance on Sunday."
While Auckland Reactor finished midfield, Purdon says he is happy with the New Zealand Cup favourite.
"He feels strong but is just a week or two behind Sleepy Tripp and Major Mark.
"But he is very settled, which is a key factor for him going forward."
He will race at Addington in a fortnight.
One of the question marks of the early Cup markets after Monday is the standing-start manners of former Aussie age-group star Sushi Sushi.
He was having his first standing start and was slow in the hands of new driver Natalie Rasmussen, a weakness he can not afford going into the almost exclusively standing-start races leading into the Cup.
With that in mind, Purdon opts for Auckland Reactor as still his best New Zealand Cup hope but has not given up on Sushi Sushi.
"He will pick up the standing-start stuff but that aside I have been thrilled with him. He is sound and working very well."
While the open-class pacers are at varying stages, trot star I Can Doosit wasn't asked for a serious effort when placed in Monday's main trot.
He is being aimed at a grass track seasonal debut in the Banks Peninsula Trotting Cup and if looks count for anything rival trainers should be more worried than ever by the great horse.
He is clearly bigger and stronger than last season and while Purdon stops short of declaring he will be better, he rates it a possibility.
"He was so good last season you don't want to say things like that but he looks amazing and has definitely grown again.
"So, I couldn't be happier with him."