OMG! FREAKIN' sooner than I thought

Ok...so here is my issue...

Going back to a company I have worked for before and knew the process of the test, bathroom etc...was confident with substitution. Now I find out they are doing the tests onsite. I am familiar with the facilities and am now a little/alot worried so I considered dilution and was reading about it when I got the call. I have less than a week. I smoked heavily until 3 days ago. Yes it is low grade weed BUT...had I been actively looking for work or expecting this I would have cleaned out and have no worries. But haven't been working in my field so it didn't matter so I thought.

My biggest fears are here:

It is a secure facility subject to search.
One or more of my co-workers/friends will be administering test and physical. And no none of them know about my vise lol they are drinkers. Scared to death I won't be allowed to lock the door.
It is a private company...very CHEAP private company but has some federal contracts.
If I fail I might as well move to China.

My questions:

Substitution or dilution?
Are there any laws on observation for pre- employment screen?
And sorry guys BUT.... I am female and HAVE to ask this question...because of the type of facility this is on substitution I would only feel comfortable ummm inserting my "sample". Once I heat it up to proper temp will my body heat keep it at the right temp? And for how long?

The thing with substitution is I have to be able to do it on the fly in case I can't lock the door. But they also trust me so that may be to my benefit.

The thing with dilution is that my current job is physically demanding so being lazy up until the test is not an option. Not to mention i am dropping a few pounds a week with this current job...lol... so LOTS of fat cell floating around my system.

Any input would be GREATLY appreciated!!

Depending on your particulars dillution may not be an option. And I would say dillution is probably not an option for you. Buts its still always a good thing to do incase you can't sub with synthetic for some unforseen reason.
They will not be allowed to watch unless you give them reasonable suspicion that you're cheating.
For me being a male, I can keep the urine at close to 98 degrees for about 3 hours just stuffed in my crotch, so you should do great there. Just practice a little before you do it. Also a lot of these synthetic urines come in a bottle with a squirt to. I highly recommend just taking the cap off when you put it into the collection cup because the squirt tops can make some odd noises when you use it.

Thanks... that is kind of what I was thinking. This is only the second screening I have ever had to do. The first one was no big deal because I was clean.