In all the time I was there all the fuel was cheap and clean except once.
Warning, the one time I filled the tanks at a posh marina and not the local fishermans quay from a tanker truck, I picked the biggest load of old rubbish you could imagine.
We got 3/4qts of the way to Los Testigos when the starboard DD92v8 shut down. Checking the Racor, it was full of water and sludge. We carried on with one engine and changing the Racor and empting the bowl every 5 minutes. Horrible.
We had to charter a helicopter to get the Boss home and wait for a fishing boat to bring out some clean fuel 3 days later. Be aware.
As to towing, no problems. Many cruising yachts tow a sportfisherman such as a small Cabo, Blackfin or similar.