Ahh if life were that simple. BTW I certainly wasn't trying to change your mind just throw out the options. After building 3 of those dual setups I ended up with a NOCO 70's as a super redundant backup that could charge a bunch of electrical units. Fully charged it holds a charge for months.
Just playing devil advocate here but if jump starting is a primary wouldn't a NOCO type appliance do the job? Much simpler than a full blown dual battery setup? Dual batteries are a rabbit hole if not managed correctly, luck not withstanding. Disclaimer, I have a dual setup but given the...
You might try a spout off another reliance product like the 5 gal blue ones that have a spout thats on reverse side of cap? I cant imagine them making a separate size spout for all their larger containers?
Personally I would lose the trenching tool and get a real short handled shovel. 3 or 4 large trashcan liners are priceless, you can kneel or lay on them and put the muddy/dirty traction boards in them too.