Maximum current draw from 12v sealed lead acid battery?
I think you will be disappointed with that battery.

Lead acid batteries are best on low rate discharge. Most these days are rated at 20hrs. That battery is rated 8Ah, so will deliver that capacity when discharged over a 20hr period, at 400mA. At higher currents, the capacity will be less. Here are a few lines taken from the discharge capacity table in the data sheet, for constant current discharge, down to a cell voltage of 1.75v (more of that later!)

current  period  capacity
  0.4A     20Hr    8.0Ah
  4.8A      1Hr    4.8Ah
 16.5A     10min   2.8Ah


so there's quite a capacity penalty to high rates of discharge.

A 150W inverter will take around 15A (assuming 85% efficiency) to deliver full power, 7A is only around half maximum load.

The lifetime of a lead acid battery, before it wears out, is strongly related to its depth of discharge. That battery rates 260 cycles at 100% DOD, ie to 1.75v. You can double that lifetime if you only discharge to 50%, and x5 if you go to 30%, that is, stop discharge at a higher voltage. Depending on how you want to use it, weight and capacity may be more important than cycle lifetime to you.

It's not clear whether you have a vehicle with you, or everything is carried in your kayak. If you have the capacity to carry more weight, then a cheap auto battery is by far the best bang for buck for the sort of currents you are talking about.

Both nickel and lithium chemistries stand up to high rates of discharge better than lead, and lithium in particular gives a much better power and energy per unit weight.