Well, talk about opening up a can of worms here.
Let me preface this by saying that you need to understand Micronesians. If you tell your Blue Lagoon dive guide that you want to dive the San Francisco on a 53 CF tank, have 30 minutes of bottom time at 180 feet, and only incur a 5 minute deco obligation, he is likely to stand there and say “yes, yes”. Because in Micronesia it’s considered impolite to say “no”. Not to mention there might be a bit of a language barrier.
Now that said, I have dived the San Francisco several times, both as a recreational (?) diver and as a tech diver. The proper way to do it would be to trot on up to the Truk Stop and hire a real dive guide who will help you plan your dive. Blue Lagoon dive guides are, well, you’re on your own. You need to plan your dive carefully (yourself), tell them what you want, and execute it yourself. More than once I have had Blue Lagoon dive guides abandon me on a dive, once on the deck of the San Francisco. Yes, there I was with my dive buddy at about 180 feet and the guide took off for the boat, with the extra tank, without so much as a wave goodbye. They dive the **** out of their guides, so they are loath to spend any more time than necessary in deco. These guys do repetitive deco dives day after day, so it’s hard to blame them. But the bottom line is that they’re the dive guide, and abandoning their charges and heading for the surface is unacceptable under any circumstances.
I would recommend that you start by researching the US Navy dive tables. They are a wealth of information and you will most likely find that you can spend more time at 170 –180 feet than you think without incurring an excessive deco obligation. This is not professional dive advice, and you are responsible for your own safety. You may want to order up a hang tank with more than 21% oxygen in it with multiple regs. Blue Lagoon will fix you up with 100 CF tanks if you ask. Make sure that you check them to insure they’re full before you get on the boat. Their 100’s are compacts, so they need to be filled to 3300 psi. Chances are they will have considerably less than that when you check them. Make them fill them full. They won’t be happy, but make them do it anyway.
The San Francisco is an incredible dive. I assume that you are comfortable with blowing PADI recreational limits and have considerable experience at deeper depths. If not, don’t do it. The only dive better in Truk than the San Francisco is the Oite destroyer.
Again, my advice would be to contact the Truk Stop and plan a day diving with them when you want to do the San Francisco.