Johan,
Before you go off gallivanting and flicking frogs and poppers in ponds far and wide around Malaysia, may I please warn you not to do it on your own. Even if you have a partner please exercise extreme caution and I strongly, strongly advise never to fish out at night in a secluded area.
Fishing is one thing, security is another. It is not uncommon to find a protected area that seems fishy and secluded, until you notice a couple of guys on a motorbike approaching you from the middle of no where carrying god-knows-what... They may have the policy of beat you first, rob you second and never ask questions ever.
If you are not local, you will stick out like a sore thumb and be an even easier target.
I would advise to stick to the pay-ponds, of which there are a few worth visiting and which are gated and more secure. Even then, they can be located obscurely and difficult to reach without a GPS/own car.
Getting out to sea on your own in this weather, given that Pekan or Rompin is a 4-5 hour trek by car and you need to find a crew and you need to be in the know to get a boat that won't rip you off and know what they are doing - these are conditions that will be too hard to fulfill on short notice without a local contact or in-depth research I'm afraid.
Sorry to say that fishing in Malaysia is not the same as Thailand.