You could probably get a straight back 30 behind the cupholder or replace the cupholder with a rodholder/cupholder.
You can connect a drain line out to the deck or down into the bilge so it does not drip on things below.
Gemlux.com makes very nice "screwless" Bluewater rodholders. You pay a bit more....
Your gunnels are open on the bottom which makes things easy.. You can install the screwless gemlux holders without the special wrench because you can get a plumbing wrench up there.
You must consider angles and space . 30 deg will not point straight outboard because the gunnel is not wide enough.
The screwless give the advantage of having a narrow flange with no screws. You can place the hole off center to give more room for a 15 or 30 facing outboard.
Always think it thru before drilling!!!!! You have to clear things below your gunnel and not interfere with the horizonal gunnel "gaffholder"
When measuring, remember that the top of the gunnel is wider than the space underneath.
here is their diagram of rodholder layout. This is a typical pattern that works for trollong with outriggers.