No pre oiler is needed for a jeep that sits only a month at a time. now if it were a year then maybe. If your not going to use it then do not start it and just keep the battery charged for when you will drive it.Every start up and run cause's acids to form in the oil that will do more harm than if you just drove it when you need it.
Half marks. Acids and such will form
and remain if the oil never gets up to operating temperature.
Ideally, you'll want to start it and maybe take a 20-30 minute drive about once every other week - this gets the oil up to heat, and also boils off the water (condensation) that will accumulate. And it keeps the gaskets and seals wet on the top end of the engine (valve guide seals tend to dry out and shrink after a few weeks, and it's easy to prevent. Ditto the valve cover gasket.)
Oil gets up to operating temperature after about 10-15 minutes, as a rule (unless it's very cold outside.) The time after that would be considered "boil-off" time - where you're literally "boiling off" any condensation and such that formed while the engine was sitting.
You'll also be wetting down the gaskets and seals (so they don't shrink and leak,) and keeping the bearings lubricated (in everything - spinning them will help circulate whatever lubricant they use. Especially in engine accessories - like the alternator, A/C compressor, idler pullys, power steering, ...)
Do you need a "pre-oiler?" Probably not - just kick it over every now and again. Pressurised auxiliary sumps are primarily used for things like heavy off-camber terrain (as ECKSJAY mentioned - the pressure sump takes over when the oil pump pickup sucks air, and it helps keep the pump "backprimed" when that happens...) or you can install a metered orifice and use it as a "shutdown oiler" for a turbocharger.
But, just starting and going for a shortish drive fortnightly will take care of what you're trying to do.