The LR3/LR4 systems are not compatible from the ABS/ESC/TRAC perspective. The spacers are an appropriate long-term solution. Based on our feedback from LR, the bearings and ball joints are more than capable of taking the additional leverage. Even the Compomotive 18s have a wider offset.
This makes sense. Yes, it's not like the oem wheels were already stretching the limits. They seem pretty conservative so adding 30mm isn't too much. Is that the exact amount? Is it the Terrafirma spacer? You're making me think it wouldn't be so bad to get an LR4.... I would actually be totally fine if a 32-32.5" tire fit ok without too much work. The Duratrac in 32" seems like a sweet spot for size and minor alterations.
I have to seriously ask you one thing though, the tire you chose, sure looks like the Nitto Terra Grappler. That size is only available in what I would call a bad-idea-load-rating of 114S. I say really bad idea considering the plans for use of the vehicle. I would not want to be relying on a tire rated for only ~2600 lbs when there are better tires rated to ~3600 lbs. How about when rocking on 2 tires in a 7000-8000 lb vehicle....worse, in one of those situations where you're truly squashing one tire with most of the vehicle.
Please let us know what you have planned as an appropriate tire choice for this project. I'd hate to see so much work only held up by poor tire choice just to make something fit.