GEO tours was used by some friends of ours for a Lamanai trip and they loved it.
www.geotoursltd.com I would advise looking around for trips, Captain Morgans is not the cheapest although I have to admit I have no complaints about them. Check in town and down't sign up for the first deal you see.
As for the 'remoteness' of Captain Morgans? I have never found it an issue although the water taxi system is often interesting to try to understand. You can sometimes hitch a ride with people which makes life all the more fun.
Enjoy your stay and I'll have a Beliken
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