If you go to
The Belize Water Taxi and Ferry Guide with Timetables, Pictures and Contacts
you should be able to find out a lot of current answers to your question.You should find which days they travel in 2020 and current pricing . (Just CLICK on that line , it is a direct link )
I have never taken a water taxi on grounds that when touring these countries on a KLR or any other mc it will be more fun to actually go the long way around by road through BZ and GT to reach Puerto Barrios .
I see no attraction in the stories of guys dragging a big heavy adventure bike onto a near-derelict of a dugout canoe to traverse a bit of swamp or sea when a perfectly good road connection exists . I will leave the water taxis to the locals travelling for shopping and work and the back-packer crowd.
I have been to Belize and GT numerous times and I have investigated these water taxi services as they pertained to Punta Gorda, Dangriga,Livingston and Pto Barrios . I have visited Livingston by using the full day launch excursion from the Rio Dulce bridge where these services start. I have visited Puerto Barrios also and inspected the harbor area. .
Note that the website I give speaks about "water taxis " because that is the most accurate description . They are by no means "ferries" with Ro-Ro service for motor vehicles .
They are passenger launches of various types with outboard motors and a sun roof .They are intended for use by pedestrians who walk aboard with their carry on baggage and take one of the seats . It is possible to carry on a bicycle and on some vessels ,NOT ALL, it may be permitted to bring aboard a small very light motorcycle which YOU ALONE are capable of lifting onboard and off .
There are NO ramps provided to roll aboard and NO cranes to lift off heavy cargo like a KLR. It may actually not be permitted to load a bike due to shipping safety regulations, load weight restrictions or insurance issues .
The site says that from PG there are runs which include Livingston on Tuesdays and on Fridays .
If you were to get a lancha ride to Livingston you would still be marooned there because there is no road or highway connection to the rest of Guatemala nor to BZ. There is, however, an actual freight boat connection from Livingston to Pto Barrios which should have no difficulty taking a motorcycle . It makes regular, I believe daily , shuttle runs between the two towns to bring all the supplies that Livingston needs and to move the automobiles to and fro.
If you are in BZ today could you ask around and find out what the status is of the Jalacte Border crossing ? Last year I found that although the BZ customs facilities and road from the Southern Highway/ Big Falls are structurally complete the GT side is dragging their feet .It was supposed to have been in service in 2016 but the GT government are beginning to stir old land claims against BZ , reverting to the ways of the old Banana Republic dictators. Sword rattling Dicks , for short . It seems as if they are wanting to take away the largest part of BZ !
. Last time after my visit BZ was scheduled for an election and the campaign of one party ( or more ) was demanding a vote to get the problem sent to the International Court of Justice for a final resolution .
This crossing would have been a boon to tourist travel to Poptun and the rest of GT and CA esp. for freight traffic .