Lewes are safe in their first season back in London Two South.
But satisfaction at assuring survival with two games to go after a 28-3 demolition of Dartfordians was tainted by thoughts of what might have been.
Lewes, promoted in a London Three play-off last year, are in mid-table but only three points off third place.
They have won nine and lost nine but scored 73 more points than they have conceded.
Skipper Dave Hemsley said: "We knew if we won on Saturday we would be safe so from that point of view it was a relief.
"We should have been in a better position than we are in, though.
"You can tell that by looking at our points difference. It's massive compared to the teams around us and better than some teams above us.
"We lost two games by a point, three by three points, one by five points and we had two draws.
"We've been stuffed by (leaders) Barnes and (second-placed) Portsmouth put quite a few points on us but that's about it.
"The difference at this level has been the bigger packs we have come up against.
"We''ve struggled in that respect but we've played some good rugby and we're third top in terms of try-scoring."
Lewes may look to remedy their lack of size with some summer signings.
They had too much guile for a rugged Darts side, not least when Sean Taylor rounded off a sweeping move for the final try.
Scott Patto, Ben Sole and Joe Thorpe also scored with Dave Tyrrell adding a penalty, a drop goal and a conversion.
Lewes can now start to look forward to their Greene King Sussex Trophy final with Worthing on April 17.
Assistant coach Dewi Vaughan was among the interested observers as Worthing beat London Nigerian on Saturday.
Hemsley added: "We wanted to have a look at them but we haven't really talked about the final yet.
"We can only how we play. We can't change things because of what Worthing do."
Billy Toone has made a lightning return for Bognor after knee surgery.
But his typically spectacular solo try could not prevent Aylesford Bulls becoming the first team to do the double over Bognor this season.
Bulls scored late to win 31-24 in London Three South East, despite a Tom Spurle try and 14 goal points by Rob Parry.
Chichester thumped relegated Cobham 85-17, their biggest win in 18 years of league rugby, though joy was tarnished by concerns over a neck injury to Justin Glue.
Ben Polhill scored two tries and Simon Bradford impressed after moving to No. 10.
Brighton expect to survive, even though a 22-6 home defeat to Purley John Fisher has left them three points clear of the drop zone with two games to go.
Folkestone can still catch Brighton by winning twice but that would mean beating leaders Maidstone, who are one point from clinching the title.
Mark Gibb kicked two penalties for Brighton but felt his side lacked the creativity to turn pressure into points.
Hooker Dan Bennett, scrum half Paul Pride and hard-working No. 8 James Wall all impressed.
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