Hi Millimoo and welcome,
Great idea, I can help now and I am quite comfortable with Indo travel. but not much knowledge about Nicaragua.
So a start , cost and length of travel Nicaragua is a long and costly journey, ( do you plan to take your boards?) Airlines are not always helpful or cheap in transporting boards, but to Indo boards are often included.
OK Lombok, August to October is slipping into the shoulder season so less heavy epic swell more suited to your needs
It is a 30 minute flight from Bali then arrange your own transport to either Kuta beach Lombok or Gerupuk or Heaven on the Planet in Ekas bay.
If you stay at a surf camp, resort or hotel they may connect you to transport there and back.
Kuta is the centre of surfing on Lombok and there quite a few homestays airBnBs, and cheaper hotel short walks from the beach. as you head east toward Gerupuk and then across Ekas bay it is more likely you will need to stay in a camp, Gerupuk has a number of camps and home stays,
Ekas has two camps
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Kuta has all the facilities of a small town and eating places, these thin out to village eating or what the homestay or camp provides.
You can be pleasantly surprised what some of the meals are like!
Some tips , do not drink any water except bottled water, nor eat peeled or open fruit, brush your teeth with bottled water ( tap water is not safe)
For a full set of tips I recommend buying the book. INDO SURF AND LINGO by the late Peter Neely, it is a fine guide for all things Indonesian and how to speak some simple Bahasa Indonesian, how to travel, surf spots on every island.
They also talk about where to stay
Now some important Jaffa tips,
Make sure you surf safety self sufficient, ther are no lifeguards and even less as you head east towards Gerupuk or Ekas.
Staying at a surf camp is a little more costly but you will have camp companions and you can keep watch for each other.
Camps often have boats that take you to the breaks and guides that can clue you in to the break.
Back to Kuta, most places you stay are pretty close to a break a, however if you wish to go further afield then you will need a guide or driver and of course cost.
Lombok is a more Muslim island so beach wear is only for the beach or swimming pool, street and town wear needs to be modest so your are not a target long sarong and no bikini tops.
If you stay at a homestay the house mama will advise you as will any hotel or resort, it is basically safe.
Sensible behaviour light drinking Ok at restaurants but watch your drinks spiking occurs,
Camps and resort supply meals and drinks and have a built in social nature. Share chat and surf.
Crowds may be a little thinner and certainly as you go east
I would recommend you check Gerupuk camps and stay online or a little more pricey I can recommend fro personal experience Heaven on the Planet at Ekas, there are two breaks there that suit your standard Inside Ekas and the sand beach break, ( slight problem only these two option)
Good food swimming pool and the exercise program of 365 steps down to the waves
Gerupuk has more wave options but I am not sure of the amenities.
Now Nicaragua the flight costs alone might pay for more time in Indonesia, if this prompts more questions ask I can answer more.
Cheers Jaffa Tidak apa apa.
Indonesian for no worries
Gerupuk has more surf options