Are their things one can do to enhance a plug?

So I've been trying out anal plugs for prostate stimulation for awhile. I can fit the biggest of the starter set I bought which is 5" long and 1.6" wide. But for prostate stuff it's a little narrow for it. So I was wondering what and how I could potentially increase the feeling.

Also, I would like advice on what is the next size I should work up to girth wise for my next toy purchase. I intend to want to work up to a 7" length, and 2-2.5" width before I move on to strap on's and real cock's because I feel if I'm use to say 5.5-7" range I could handle most normally endowed people/toys.

 

I can recommend two things:

1) njoy pure plug large and 2.0

2) e-stim moaner insertable, just the insertable is a lot of fun, adding e-stim makes it tons better (of course, I get that this may be a bit much for some). I've got the Moaner in right now, and it's hitting just where it should.