That's a cool trick!
My advice would be, although folks have done it without taking off the rear bumper, it really isn't that much work to take off the rear bumper and it gives you a lot more room.
Clamps:
For the "test pipes" - I'm not sure what comes with your brand or pipes, but a 2" Easy Seal is a better fastener than the little clamps that came with the Top Speed pipes I got.
For the "u" pipe that connects the test pipes to the muffler, my clamps were very corroded, so I got these from Amazon:
https://www.amazon.com/gp/product/B00317DKWO/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
Another consideration, that I don't have any hard data on, is that the stock 2nd cats are shielded but the 2nd cat delete pipe is not and can radiate a lot of heat into the inner CV Boot, and also the inner rubber bushing on the rear LCA, so you may want to evaluate that and see if you want to add any shielding.
My first approach was heatshield armor as documented here:
Use Heatshield armor and stainless zip ties for test pipes to shield inner cv boots
Since then I sent all my exhaust out for ceramic coating and that made it slippery I guess and the heatshield armor would slide around, where when on the bare stainless it stayed in one place so for now I am using just the ceramic coating and the heatshield is uninstalled.
It is a hassle to work on these pipes once installed so if you were going to wrap, or do something like a Swain coating or a Jet Hot now would be the time.
Looking forward to the report after you get it installed!