Yeast experiment recipe

Hi there everyone, been a while since I have had time to brew anything but now that spring break is here I am hoping to do an experiment I have been planning for a while. What I want to do is make a 4 or 5 gallon batch and split it into 4 or 5 one gallon glass fermenters and put a different yeast in each. I see this as basically a SMaSH experiment on easy mode. Problem is, I have never made my own recipe before and am looking for advice. I am hoping to do something single malt and single hop that is nice and clean so the differences the yeast puts out are not overwhelmed, but also something that would hopefully be versatile enough that I could use it in the future as a starting point for hop and malt experiments in the future. I am planning on doing this as an all grain brew in a bag (my first) so that I have more control of the final outcome. I would appreciate any advice you guys could give.


Misc questions:
I have seen instructions with a 1 gallon kit that said to only use half the yeast bag. Is there a reason for that? You will be throwing the rest out anyway so is there a reason not to just put it all in the fermentor?

What yeasts would you suggest I try in this experiment? I plan on using US-05 as a clean base of comparison and probably a belgian to really highlight their distinct characteristics, but havent done much like this so I don't know others that I should be interested in.

You could just use 2-row barley as your base and add some hops for a basic base or add some carmel 20 in there for more flavor. I think WlP300 is a pretty interesting yeast it has a lot of esters. Maybe try a high attenuation strain and a really low attenuation strain. You will want to make sure your using the same pitching rate on each fermenter. The reason for not using the whole packet of yeast is that it is possible to over pitch yeast. I suggest reading the book "yeast". Its pretty interesting and has a chapter on setting up a yeast lab.

I would do a low hopped Pale Ale, then you'll emphasize the yeast flavor. Blonde might also be interesting.