I think people are making this a bigger issue than necessary. from a previous closed thread:
Hey, quick question for those with some plumbing expertise, would it be possible to use an offset toilet flange as mentioned above with your standard RV toilet? When the RV was originally built they placed the toilet's stack way too far forward in the bathroom leaving very little room for one to actually sit down. I'm planning to redo the wet-bath in the camper here soon and was wondering if one of the above mentioned flanges could be used to shift the toilet back 1 1/2 - 2".
I've been looking at the use of elbows to move the throne back towards the wall (Has a 4"+ space between the back of the john and the wall) but to use 3" elbows at a max of 45 degrees would add considerable height to the toilet. I haven't been able to find a regular 3" abs fitting that simply does what two 45 degree elbows together would do to shed some of the height.
bumpy