although the weight is a bit high, I suspect that more weight on the front would be better to counter balance any weight from a trailer. i now own two trailers one is a burley nomad, which im not concerned with, and the other is a bob yak which ive read in other forums that it takes weight off the front of the bike when fully loaded and makes it more difficult to steer on soft ground so instead of taking weight off I actually want to add as much weight as possible to the front of the bike so the surly rack should work well.
It is high in two ways. First it is double the weight of most lowriders and second the weight is up high. I can see wanting a rack top for light bulky items, but you are using a trailer so you should have an abundance of space for bulky stuff.
It isn't hard to get some weight on the front wheel by just using smallish panniers on lowrider racks and putting small dense items in them. The advantage of the weight being low is significant, especially in the front.
Think about this... A BoB Yak weighs 13.5 pounds and a Surly Nice Rack weighs 2.95 pounds (slightly more or less depending on which hardware your bike needs) add an extra inner tube for the trailer and you are up close to 17 pounds. There are people who manage to tour carrying less than what just the trailer and rack add to your load!
If there is one thing that I learned while riding the Trans America and other shorter tours it is that weight carried matters. A pound or two are a big deal and a few ounces here and there quickly add up to pounds. If you take too much "stuff" you can always mail things home, which many tourists wind up doing even after they are pretty experienced. If the weight is in racks and trailers it isn't that easy to reduce the load.
I don't know your experience level, if you have logged tens of thousands of miles happily hauling hundreds of pounds of stuff, ignore me. If you have not yet done a multiweek tour, please at least consider my suggestions one more time.