Weight placed half-way between any 2 axles will be split evenly between those 2 axles. The closer it is to any axle, the higher proportion of it's weight will go to that axle.
So, a 30lb propane tank (close to the hitch on the tongue) will have more effect on TW than 30 lbs of stuff in a forward holding compartment (in the camper). So if you are trying to increase TW, you want to add weight as far forward as possible.
But if you must add some weight, but don't want to impact TW, try to keep it close to the axles.
If you must add some weight, and would like to decrease TW, put the weight as far behind the axles as possible.
thebrakeman ('70), DW ('71), DD ('99), DD ('01), DD ('05)
2004 Surveyor SV261T (UltraLite Bunkhouse Hybrid)
2006 Mercury Mountaineer V8 AWD Premier
Equal-i-zer WDH (10k), Prodigy Brake Controller