Ross had to field a 16-year-old striker in Rory MacLeod against the Black Cats due to a small thigh injury for new signing Steven Fletcher, who is one of three arrivals already in the door alongside midfielders Craig Sibbald and Dylan Levitt.
While Sibbald played 60 minutes, Levitt joined Fletcher on the sidelines with his own injury and while neither are serious, Ross is keen to add at least four new players before the competitive action begins on July 30 away at Kilmarnock.
“We need bodies, there’s no doubt about that,” said Ross.
“You can see where we are squad-wise, we had 16-year-olds starting today and when you looked at the bench with the exception of Nicky Clark, there was nobody over 21.
“So we have a very young group and we need reinforcements.
“I think we need at least four outfield players, you can see that. Hopefully we can get them in soon.
“The Scottish Premiership isn’t an easy league so you need that depth of quality and that’s what we’ve striving to get.
“It has been harder playing catch-up because all the work I would have done at the latter part of last season and into the early summer I wasn’t able to do because I wasn’t here.
“We are chasing a bit and that makes it harder because a lot of the ones you would have identified go and you have to find others.
“You can always sign players but it’s just making sure they’re what you want quality-wise. We have tried to be patient but we need numbers in.
“We would like to get some of the young players out on loan to help their development but we can’t do that at the moment.
“That’s not because they are not good players, they need experience.”
United are expected to complete the signing of Central Coast Mariners goalkeeper Mark Birighitti next week. The 31-year-old is still in homeland Australia but Mariners have already admitted he is leaving for Scotland, with an Italian passport expected to circumnavigate any visa issues.