To be honest, I don't know the exact layout of the first elephant house at the zoo. It was designed by Frank Furness and built in 1875 and
I found an image online, but can't find a blueprint for it as to how the stalls inside were organized. I just know that it was the two female elephants followed by Bolivar, then Pete the rhino so my design isn't exactly correct. I just went by the very few photos I could find. Furness also designed a restaurant at the zoo and the entry gates which were slightly altered but still greet visitors to the zoo today.
It also appears on this map from 1907 that where the buffalo paddocks used to be was replaced by the Paul Cret elephant house. Now I could recreate that much easier than the Furness structure and having visited the zoo often from my childhood have many fond memories of Petal, & Dulary the elephants, Xavira & Sanjay the Indian rhinos, and Cindy & Unna the hippos.
And yes that was me in the vid. That is my favorite Philadelphia Zoo memory and the first time I was that close to an Indian rhino. I miss Xavira!
Here are the blueprints for the 1940's Paul Cret Elephant House but you have to pay to access them.
As for Bolivar on the grass, I put him there for a clear full body photo. There might have been one or more instances early on where he might have gone outside but I don't know for certain. That's too bad about your computer. I hope Geek Squad can fix it. In terms of Bolivar's mounting from Bonnie's Twitter photos it seems that McCadden just made a crude structure to mount him on not making a lifelike form including the musculature and fat deposits like you said. The first time I saw the pic of his mount from the Academy's blog, I thought it could've been the real life version of a heffalump from Winnie the Pooh. Its that bad!
Oh and by the way, I tried logging into Newspapers.com with the old connection I used to have to look for articles. It didn't work as the subscription that my old work colleague had was only good for 6 months and must've expired some time ago.
The National Zoo is a lot of fun. I was last there in Sept 2016 before Spike came. I saw him at Busch gardens in winter 2017 before he left, but never got the chance to see him closeup to appreciate his full size as the habitat is lower than where you're standing. I really enjoyed watching the elephant cam of when he came in spring of last year and how much Rani and him were "in love". They make such an adorable couple! Also when at the zoo, they have a Lesser Kudu calf as well as Amur Tigers. I'm curious if giraffes and rhinos will ever make it back to the zoo.
Spike & Maharani
National Zoo by me. (Asian elephants appear at 30:15)