Inside and outside will have different needs as far as what the speakers are being asked to service.
Inside, following the advise above and knowing what will fit, look into the Focal brand. If on a budget, watch for Craigslist deals on these.
Outside you are into a smaller subs of speakers. What I have seen down successfully accomplished, is the leaving of the OEM speakers, but just disconnect the wires and stub them outside of the OEM speakers for easy access. Then look for a speaker that will easily fit into storage, add mounts below or to the sides of your OEM speakers, and then when in camp, pull your speakers out of storage and mount them on the wall mounts, of course with the wire's clamped into location. You're looking for weather resistant, with I recommend a wide dispersement speaker. I've had good luck with the Boston Voyagers, as well as Infinity Outriggers. If you watch Craigslists, you can sometimes find the outdoor B&W's at a decent price too.
Of course, I like tunes. I like good sounds. I do not use them in campgrounds. I use them when boon docking and not bothering anyone near me.
In campgrounds, I use the JBL Extreme via Blu Tooth. I have two of the them, set up in stereo mode. Good overall sound quality, without needing to 'crank' the volume. I can sit outside at campgrounds, without impacting anyone around me, and still have relatively good sounds at lower volumes by using these. (They are battery powered, and batteries will usually go two to three days between needing a recharge, or more.)
Best of luck to you, and regardless of what way you go - enjoy the tunes