Without full understanding about clearances and dimensions (of the tank) as well as were frame cross members are, I can't say anything for certain. What I can say is that the tank can always be cut up to remove, although getting a new one in might be problematic. I really don't understand why your rig can't be jacked up and (if needed) a cross bar unbolted, or worst case, cut and rewelded. This whole thing makes no sense to me.
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