The Hawks are envisaging a sizeable crowd of potentially around 3,000 for what will be their final home game of the season on Saturday.
There is so much riding on it for Doswell's side, as a final-day win or draw against Chippenham will secure a seventh-placed finish and a play-off spot.
But the visiting Bluebirds - sitting in eighth position - know victory would see them claim a remarkable play-off place.
With such a high stake occasion ahead, Doswell believes it's crucial 'everyone who cares about the club' - along with those looking for a early May football fix - head to Westleigh Park to get behind the Hawks.
'People from within the club think there's going to be between 2,000 to 3,000 people here which is going to be huge,' Doswell told The News.
'I know Chippenham, to their credit, they've already sold their first coach to come down and they'll come in some numbers.
'If anyone can get down here on Saturday to help us, it would make a huge difference, (entry is) just £6 for Pompey season-ticket holders, we've given out all the 'FlexLeigh' tickets as well.
'It'll be great for every person who cares about the club to come down on Saturday and cheer us on.'
Hawks secretary Trevor Brock is calling on anyone attending the game to arrive in plenty of time.
‘Please don’t turn up at ten to three and expect to get in as you would normally do,’ he stated. ‘People will need to arrive early.’
To cope with the expected demand, the club will have eight turnstiles open - three more than usual.
The Westleigh pub will also be open at 11am - an hour earlier than usual - with possibly an outside bar if the weather is nice.
Brock is also warning supporters not to park on the verges outside Westleigh Park ‘as the traffic wardens are normally out on occasions like this.’
The crowd on Saturday should hopefully beat the current seasonal high of 1,711 recorded for Dorking’s visit in early January.
The last time Hawks attracted a crowd of over 2,000 to Westleigh Park was in March 2019 during their one season in the National League. Back then, 2,058 saw the defeat to Leyton Orient - the O’s fans bringing several hundred fans en route to winning the title.
Hawks’ seasonal league average this season is 1,198 - a couple of hundred down on Doswell’s first season in 2019/20. But Hawks were sitting in the play-off places for most of that campaign, compared to this season when they haven’t.