creating multiple experimental batches

I am playing around with ingredients and I'm wondering how best to approach this scientifically. For example, say I wanted to try out different combinations of spices, while keeping everything else the same. Say I use 5 one-gallon fermentors. It is recommended that spices are added 5-15 minutes before the end of the boil. Understandably, I don't want to boil 5 separate batches. So how do I go about separating the batches? I could dry-spice, but that wouldn't result in the same flavors as boiling them. The best method I could think of is to boil the spices separately in my kitchen, but I'm concerned that I would be missing out on some of the chemical reactions between the wort and the spices that might contribute to the flavor. What do you guys think?

I think you answered your own question! If you don't want to boil 5 seperate batches, boil 2 or 3 and dry spice the others. Maybe even use the same amount of spice in seperate batches with 1 boiled and 1 dry to understand how spices behave under different conditions. You could do this with 2 different spice recipes and then pick one of the two to attempt the seperate boil then addition. That gives you 5 different batches with only 2 boils and direct comparisons. Have fun!!!

That might not have come out as clear in print as it did in my head

Batch
1--Boil spice combo 1

2--dry spice combo 1

3--seperate boil spice combo 1 (or 2)

4--boil spice combo 2

5--dry spice combo 2

I'd boil and chill all 5 gallons together and transfer into each fermenter (I'd probably use 6 so to leave enough space for krausen).

Then boil up 6 cups of (or 5 if your set with that) water and put your spices in 6 (5) different coffee cups. Add a cup of boiling water to each cup and steep for however long you need want. Then add one cup of tea to each fermenter. Make sure you take this into account so you hit your OG.

Another option would be to save 6 cups of wort aside and bring that to a boil and steep like above. Would be easier to hit OG this way.