Parallel Dual battery setup

I know that there are many different ways to set up a dual battery system.

I am needing to replace my battery so I was thinking about getting an optima yellow top battery X2 and wiring them parallel. Any one done this before?

From my guesstimating the two optima batteries will fit and not interfere with the cooling lines from the s/c

but i have to get a bracket system to get this setup and id like to know if you’ve done it what battery holder and if you used an isolator or not ?

I see the off road alliance system which is really expensive when you include the batteries. What are the advantages of this type of setup vs. the parallel setup I was talking about.

Thanks in advance
I’m just spit balling ideas