Chaz, you get an A+ for effort!
I think the only way to get enough access will be to pull the engine. Unless you have other reasons to do so now, I'd wait until you need to tackle that job. Yes, it will drive you crazy thinking about that dowel pin, but you'll be able to scratch that itch in the future.
I doubt if your decision will change your oil change frequency. We pamper these trucks and tend to change oil sooner than realistically necessary.
If you install a bypass filter, many will argue that it is better than a full flow because it eventually filters all of the oil through a much finer screen than a full flow. Full flow does all the oil all the time, but catches larger particles than the bypass. Full flow never gets the fines out of the oil.
If you ever pull the engine and have access to the dowel, you'll have the option to plumb both a full flow and a bypass. If you install the bypass now, your equipment will not go to waste.
Matt
