I don't see them having an evening ceremony. Especially a late evening 'candle light' one. Among other things that severely limits a reception, especially with the older guests like the queen.
It has become quite popular, especially among the upper crust, to have two receptions. Not simply a royal wedding. Pippa is not alone in having a wedding breakfast and later an evening reception. These are the circles Eugenie and Beatrice move in, as much as their cousins do. Though the wedding will be at a much smaller scale then Harry's, I expect both. I wouldn't be surprised if we see the same as Harry, in that the queen will host a royal lunch at the castle (smaller scale) for the official event. And an evening party hosted later for the couple and their friends, by Andrew, possibly at Royal Lodge.
No need for Eugenie's wedding to be downsized even more then Harry's, just to make it as different as possible. Its not going to compare anyways, day or evening.
I also think Eugenie will want a carriage ride, and a candlelight ceremony doesn't suit that at all.