Can I switch battery types (for example – remove Lead Acid/GEL/AGM and install LiFePO4)?
This is potentially very dangerous. Charging and discharging characteristics of Lithium batteries are not the same as other types. Further consideration is current draw, cable size and location.
The standard requires a warning label stating that a battery must only be replaced with one of the same type and specification AND that battery upgrades MUST only to be undertaken by a competent person (ie appropriately qualified and/or licensed electrician).
For details go to Appendix C and clause 5.4.2.