+1 on replacing the oil filler gasket annually.
PS - don't do it if you have a PCV problem though. It will /increase/ the pressure in the crankcase and just cause the oil to push past more expensive (to replace) seals.

In your situation I might think about tying a rag around the oil filler 'neck' to catch any oil that pushes past there.

Maybe for your trip you could do the same thing on your dipstick to relieve some of the pressure. Like maybe, lift up the dipstick enough to disengage the seals, and then tie a rag around the 'gap' letting the vapour pressure vent but hopefully keeping the oil inside the dipstick/rag?

I don't know how safe any of this is... oil soaked rags and hot engine parts - seems risky. Also, you'd need to make sure the rags wouldn't get entwined in the rad fan.

There is the potential for a surprising amount of oil to bow out the dipstick, and oil in your engine bay will make a big mess, not to mention eat up electrical insulation and paint, and will quickly ruin your alternator, as I discovered last year.

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1998 V70 AWD->FWD Turbo 200k+