Hmm... I'm hazmat certified but never thought about it's kinky use. 😃
Anyway, stretching. Use lube and take it slowly and go up in size little by little over time. Plenty of time. Use lube.
Try warming your (bigger) toys in warm water and take a nice warm bath and get as relaxed as possible. When not relaxed the spincher close tight. 😃
Use lube and again slowly go up in size. Sooner or later you trained your spincher and it becomes much easier. Than advance etc.etc
It took me many years to get to my 10 inch circumference. I can now start with big toys that took me a year or two to get to.
As a matter of fact, it took me probably 3 to 4 years to finally get the Ace of spades inside me.
I recently bought 3 new toys to train to the next size, 11 and 11.5 inch circumference, even an 12 inch. I'm not expecting these to fit anytime soon.
Lube luve lube.. lots of lube and relax.
Hugs, and happy plugging my dear.
edit...
I forgot you asked about "cleaning". I have a 2qt enema bag from Walgreens, or any other pharmacy. I use plain water and on average I am clear and clean after 3 flushes of 2qt each. One time I added one 2qt on top of what I still had inside, so anywhere from 3 to 4qt. plain water. I was clean alright. 24 hours later, at work, I thought I had a little fart but it was the remaining water. 😃 So my limit is 2qt water each fill up.