But he insists that the team 'want to finish the season on a high' despite the atmosphere now being 'less pressured'.
Reflecting on the hard-fought victory, Coulson praised the attitude of the players and highlighted the importance of the victory for Sussex Rugby as a whole.
He said "Dings are a very strong side with threats across the field. Their forward pack are considerably more experienced and sizeable than ours so the effort from the pack can't be understated and was integral to the win.
"Securing National League 2 South Rugby for next season was huge for everyone. The players, coaches and staff have worked tirelessly to maintain our status. It is vitally important for Sussex rugby to have a club playing at National League level, giving local players an opportunity to test themselves at level 4. It affords any aspirational Sussex or Hampshire player a pathway."
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Coulson knew that Raiders' performance was below par, especially in the first half, but said that 'effort' and 'moments of brilliance' were key to picking up the 5-point victory that was 'cause for celebration'.
The assistant coach said "After the game we all agreed the performance was in the 'Jekyll and Hyde' category. Portions of the contest were bad. It was clear two teams under pressure fighting for their survival were struggling to find any rhythm, but this was tempered with moments of brilliance. We scored tries that any team in the league would have been proud of."
"It would be unfair to highlight one individual but it would be fair to say the forwards managed the challenge they faced admirably and the backs looked dangerous when on message."
Discussing the season's performance as a whole, Coulson admitted that Raiders haven't quite reached their potential, but is still impressed by the team's output in games.
He said" We appreciate we have the potential to challenge teams throughout the league when we are fit and firing, unfortunately we've been neither for large portions of the season."
Looking forwards to their home game against Taunton on Saturday, Coulson insists that the team are keen to finish the season strongly and are determined to please the 'huge crowd' that is expected.
He said: "We want to finish on a high. There will be a huge crowd at Raider HQ for the last game of the season and I dare say most of them will be keen to see a home win. We have to respect the fact that people invest large amounts of time and money in supporting us, so we need to honor that in our preparation during the week and performance on the pitch."
"I won't use the word relaxed to describe the environment now we're safe, less pressured is more accurate. But we'll never stop working, Saturday will be another chance to produce our best performance of the season."