We've had our Roo 183 for 3.5 years and love it - but just could not figure out where to install the toilet paper. We finally found something that is working great for us and I thought I'd share.
The TP holder is from Ikea (Grundtal for $5.99). My husband made a small wood triangle that is screwed into the studs in the corner, then the Grundtal TP holder screws into that. Adults and kids have been able to reach it without issue.
GRUNDTAL Toilet roll holder - - IKEA