Been twice and hope to join Stoo in a three peat some day soon. Problem is, Placencia is just too much fun to pass up.
You could maybe get away with fishing on the "service" side of the island. It's not like they would kick you off the island, lol. But if you're diving, you won't have much time to fish anyway. There are no rocky points, btw. Either sand or mangroves.
Take some bug repellant, but you probably won't need it because the wind rarely dies down. But if it does you'll be glad you did.
Tipping is a bit of a sore subject. I don't know that I would call it pressure, but in your room or cabana you'll find a "Suggested Tipping Sheet," which will give a suggested range of tips and will include everyone from the diving/fishing guides, at the high end on down to the housekeepers (so far so good) to the kitchen staff (hey wait a minute, they double as the housekeepers) to the maintenance crew (seriously?) to the groundskeeper crew (hey, wtf?). The service is excellent, and I consider myself a pretty generous tipper but I've never tipped a maintenance crew or groundskeeper. Use your own discretion. It's not like anyone's going to hassle you or even ask about it.
Keep in mind that tipping is a nearly uniquely American custom. I have it on pretty good authority from a number of sources that almost no one else tips. The crew and staff are aware of this, but I've never seen any difference in the level of service, which is to their credit. And TIR attracts people from all over the world.
The drinks are high. I think taxes and gasoline have a lot to do with it, but they do take advantage of a captive, thirsty audience. So I tend to hold off drinking, then party like hell with the staff on a night of our choosing. We kept George the bartender up to 3 am the first time. The second time the owner had instituted a (stupid) no fraternizing with the guests rule on the staff, so we partied at their quarters. Management can stop the staff from hanging with me, but they can't stop me hanging with them. Ask Uncle John about walking down the stairs backwards. He'll get a big laugh. Those guys work hard, and they play hard, too.
Say hi to Brad, Marcel, John, Daniel, George and all the gals for Downing and Carol. Tell Brad I'll likely drop by Cheers August 15 or 16 if he wants to hook up.
You're going to have a blast. Be sure to write a trip report.
Don't forget your flip flops. Leave them at the Lodge, so you can wear shoes to dinner (and kick them off under the table once you sit down). It's always a strange feeling putting on shoes again upon departure.
You could spend your time in Belize City fishing like these guys, right off the Swinging Bridge:
Make friends with George, the bartender. He'll treat you right.
P.S. Regarding the advice about Customs, that must be new. I haven't heard of any issues with cameras, laptops, etc. It's not as if you can buy that stuff down there, at least not easily, and I've never had Customs even peek at my stuff. I think it's a non-issue but would love to hear if anyone's had a bad experience lately since I'm headed down there soon.