Battery Recommendations - Sanger V215

I am looking for some recommendations for a battery setup on my 2014 v215. I currently have (2) dealer installed Interstate 24 marine batteries (why both 24's is beyond me) located under the rear bench in their stock locations wired to a perko switch. I am in the process of acquiring 3 Arc Audio amps for eventual installation. (Ks300.4 x2, ks600.2)

The stock locations do not appear to support a larger size battery/box (Group 29). Is this correct? If so, where/how have you wired up additional batteries (I assume under the observer seat)

If they do not fit, I was going to move both starter batteries to position 1, and add two deep cycle Group 29's under the observer seat and wire them to position 2. Then wire up a Promariner Prosport 20 2 bank charger to the Group 29 batteries.

Would I just wire up the amp B+ thru a fused distribution block + ANL fuse back to the Group 29's wired in parallel? Or do I have to wire back to the perko, located on the forward wall of the engine compartment? Also, where are you routing your power/grounds for this?

Thanks in advance.

I have 2 deep cycle group 27 in the stock location think they are around 110amp/hours each. I removed the ends of the battery boxes and they are the biggest that will fit.
Running arc 600.2 to towers + jl 900/5 to sub + interior. Have promariner 20 also and seems adequate for what I need.

Where are you wiring your amps back to? The batteries or the perko switch?

just use the ski locker like i did!!! lots of room for lots of batteries!