Looking at at 2013 B5 and my 2015 C5, they appear to be the same. Although with running improvement some of the "gut" may be different.
Having recently pulled mine apart on a 2014 C5, unless something has changed, you will need to fully dissemble to get them back together. The bottom bolt will allow for draining, but from what I recall will be next to impossible to retighten unless you can hold the fork piston in place somehow.
Ether way full disassembly was no big deal.
Let us know how it goes.