You ALSO might want to do some towing with it full and empty before you make that decision since if your FW tank is in the front, they MAY be a reason for it being there. could be your tongue weight is heavy enough only with it full. Some smaller trailers build in ballast by using the tankage for the purpose. Once you find out how it tows best and what your weights are, then as suggested, set it up in that mode. IF your trailer is not a small one, then you can likely forget about the issue as weight distribution is not usually a concern.
2011 F-150 HD Ecoboost 3.5 V6. 2550 payload, 17,100 GCVWR -
2004 F-150 HD (Traded after 80,000 towing miles)
2007 Rockwood 8314SS 34' travel trailer
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