Even with 406s you can fit some big bags just need to measure from the top of your rack to the ground. Since you have a trike you might be able to go a little lower than a 2 wheeler that might lean alot.
Here is my hurricane with some panniers and it does look a bit higher than it would be if I was sitting on it compressing the suspension these are regular front roller classic ortlieb bags.
Dimensions: 12 x 10 x 5.5in (30 x 25 x 14cm)
Max Capacity: [Pair] 1526cu in (25L)
I don't have a picture but my big arkel 42 liter bags have been used without much of a problem probably due to the mounting hardware being a bit lower on the bag so it isn't that much closer to the ground than the ortliebs. Course it doesn't have the cinch strap to pull the bottom up tight and it makes it look like I'm riding cross country but it works.
•Dimensions: 16" x 17" x 7 " (H x W x D)
•Volume: 2550 cubic inches/42 Liters (per pair)
If your just looking for a little room the toploader bag with the roll down panniers would work great. My wife uses a similar one and switches it between her cyclocross bike and trike without a problem and it works on both great.