Blackburn raced in for three tries in 15 minutes at the end of the first period as the visitors stormed to a 43-12 win.
Senior coach Will Knight felt it was a fitting end to a season of progress.
He said: ‘It was a fantastic performance considering we were forced into a number of changes.
‘The most encouraging aspect was the fact that all the players who stepped up played out of their skins.
‘Though our position in the league is slightly below that of last season, I feel we have got stronger on a number of fronts.
‘We have a wider player base to choose from and there is greater competition for places.
‘There has also been a change in the mindset of players who are starting to take greater responsibility.’
After an even opening 20 minutes Havant rocked their hosts with two converted tries in as many minutes, with Blackburn claiming both.
Luke Barfoot drove over from a five-metre scrum and straight from the restart forwards and backs combined to put Blackburn over for his third try.
The second half continued in largely the same vein with the visitors adding further tries from Darren Bamford and Ben Brierley.
Bamford capitalised on a bursting break from hooker Jerome Trail and Brierley smashed his way through in the closing minute.
‘To score six tries and get a first ever win at Dover is a perfect way for us to finish the season,’ said Knight.
In London two south-west Portsmouth crowned a successful first season in charge for Ben Dudley with a 28-25 win over Warlingham at Rugby Camp.
It confirmed fifth spot for the city club – their highest finish for a number of years.
Outside-half Andy Barnes proved the architect of the home side’s success, contributing 18 points.
Barnes scored a try, three penalties and two conversions with Jackson Clark and Tom Whitehouse adding the other two tries.