Tim,
There's one thing to consider when you make modifications like this. Lippert's view is that doing so voids the warranty. Some people will note that if there's a problem, the burden is on Lippert to prove your modification caused the problem. But once the 1 year frame warranty expires, that's a moot point.
Frame problems do happen occasionally, and as a goodwill gesture, Lippert may step in and provide assistance after the warranty expires. I doubt they would do this if you modify the trailer in a way they don't support. It won't matter whether the mod caused the problem. Since they're not obligated to help, they can simply decline, pointing to the expired warranty.
Many people have gone ahead with hitch mods anyway, without having any problems. So maybe you'll be ok. But you should go into it with your eyes open.