That depends on if your body will have stretch marks as you gain. some get them some don't.
Usually a rapid gain will cause them.
I never got them myself and I'm obese.
I have cellulite in abundance but no stretch marks.

Everybody is different in how they carry their weight so there is no way we could say how much weight it will take.

Most of the guys I dated were in the 300 350 range.None gained or lost during the relationship.
I dated one guy who was very athletic and I got him to gain 20 lbs or so but he didn't like gaining on himself.
When we met I was 115 and when we split I was 250 ish.
He had no problem with me gaining and if it was what I wanted he was fine with it.

If you want something bad enough you will do it.
Saying you are conflicted means you lack the will to do it.
Everybody seems to be conflicted these days or they make up excuses for not doing something they want to do.
There will always be people that don't approve of things you do and you can't change that but are you going to let them run your life for you?

You are a semi buffed out skinny guy Kkt and I am an obese woman who used to be a gainer that started off skinny. So who would you take advice from if you wanted to gain?

We can agree to disagree and I am good with that.
If there were a supplement that actually worked well don't you think you would have found it in an online search?
Also wouldn't it be a well known thing in the gaining community?

There always seem to be this idea that there is some magic pill to make you get fat or to make you eat more.
In order to gain you have to eat more and it takes effort on your part to gain.
If you aren't willing to commit to it then you shouldn't gain.

I would love to know if classmates ask if you have gained weight.
Or asked if you were pregnant like SahX suggested.

I never thought of such a thing but if you guys can do it I think thats amazing.

Just remember weight gain takes a while its not an overnight thing It might be a month before you see any tangible weight gain that actually sticks.
The main thing is keep to your plan and don't give up.
You might get discouraged and think its not working Just don't give up.

Like nate said don't over do it at first because your body isn't used to it. You need to start slow with the heavy cream and build up to it.
Snacking more in between meals or eating larger portions at meal time always helps too.
I would have no idea about what your wife notices.