I think for the money having lifepo4 would make for a better long term investment, also the AGM I can only use half the capacity right so it's really only 52ah of useable storage isn't it?
Could be better investment, depending on how deep it is cycled and how often.
For OP's case, assume every night.
According to AGM manufacturer's manual,
350 cycle 100% DoD (1 year)
650 cycles 70% DoD (not quite 2 years)
1800 cycles 30% DoD (5 years)
30%, 30 Ah is 400 Wh, over a 12 hour night is 32W average, or there about, for 5 years lifespan.
Depends on what loads are planned.
LiFePO4, if everything goes as planned, could be 80% DoD for a decade of 80W average draw.
5x as much use for similar price.
I believe in KISS, so if AGM meets the need that is what I would suggest. Just kicks a can down the road for 5 years.