To me, it is a sin to add any non-functional weight,
but understand your motivation and short-term need. Even so, I will make another run at redistribution or a portion of.
Take one of you 6 gal portable tanks and move it to the furthest forward, on floor, or if that is a lower deck. Latch it down. Since you are not in the bow, the above deck placement should not be in the way. This will transfer about 37lbs from the stearn to the bow, and would be the near equivelent of adding dead weight of 74lbs. This can be easily reverted back when fishing with two people, and when you sell it. You would also have to transfer tank back once primary is used up, but it sounds like your trips might not even require it. You can extend the primer bulb hose length real easy and for these solo trips, shouldn't be an issue with above floor hose.
If on these specific fishing trips you are not using the trolling motor, consider something similiar for that battery, as well. That would be an even larger weight transfer, but if you are in rough water, might not be the best thing for the battery. If you are able to do both of those, I doub't you would need any more additional weight. Also, you have everything you need to do a test asap.
John