10% slower is about what you'd expect for a tricycle compared to a bicycle, all else[1] being equal. A recumbent trike gains a bit aerodynamically over an upwrong bike, so it's not quite as bad as an up-even-wronger trike.
I'd suggest getting a 100km ride under your belt before attempting a 200, but as ElyDave says, what's the worst that can happen? You're clearly no stranger to endurance riding, just bear in mind that you're likely to be working a little bit harder than you're used to.
[1] It's mostly in the tyres.