Your vanity is not very deep at only 18". Unless willing to give up some closet space I don't think you can closet the toilet.

What does a large shower mean to you? Do you have patterns for the toilet and the shower? That makes for an easy alteration/options. That vanity will be pretty shallow at 18" but I've seen someone do it several years ago on GW and it was beautiful. I think it is not recommended to have a vanity at the door like that, someone will be in the way with the door swing.

There are specifications used for distances needed for elements in the bathroom. take a look at this site:

http://starcraftcustombuilders.com/bath.design.rules.htm

Is the vanity already installed? Maybe this can work for you.

If the closet were smaller, you might have options.

Shower would be 5' x 5.5'