Plugging Adderall?

I am planning to take 2.5mg of adderall orally and then plug 7.5mg. I have never plugged before and am intrigued to try it.

I saw someone on r/drugs talking about a cold water extraction of Adderall for the purpose of snorting by mixing the Adderall with water so that the amphetamines dissolve and separate from much of the filler which floats on top. My plan is to take the 7.5mg, crush it up, stir it in 7-8ml of water, suck it up into a disposable syringe that I've used for making cannabis edibles before, and then using lube, insert it into the anus and plunge. I'm assuming I'll need to clench my asshole for a bit afterwards to hold it all in, not sure if there's a process for this. I've done a bit of anal play before so I get the general idea of putting something in my ass. I plan to take the 2.5mg orally right before attempting all of this.

Any suggestions/advice? Is there something I'm missing here or a better way? I'm very excited to try plugging and a faster ROA than oral. I've tried crushing 5mg and taking it sublingually and that was pretty nice.