The mandated weight distrubution last year has helped alot, however i think ballast rules can be tightened up a little futher.
I am an advocate of a maximum weight with and without fuel. I belive that the car should weigh 650 kilos without fuel as the minimum, but no more than 655 kilos without fuel.
As for fuel, tanks should hold a mandated of 100 kilos. However id also bring back refueling, with a DTM style shoulder filler that is filled with 20Kg for each fill, cars can have 2 attached from each side of the car to give 40Kg per stop. Id mandate that the engine be switched off when the fill is in progress, and fuel stops be seprate to tyre stops and make stops for fuel last a mandated 10 seconds. Cars would be weighed before the went straight to the grid, no passing thru the pits twice to reduce the fuel load to an optimal. But the fuel rule is more a dream of mine to spice up racing even futher.
I belive the ballast should only be allowed to be be held between the front wheel and rear wheel centre lines, nothing forward or rearward of theese points, and be held no more than 50mm higher than that refrence plane.
The result of this would be for teams to weight up the benifits of aero gain Vs tyre performance. McLaren for instance could have a tyre advantage with a low nose being able to change arround ballast in the region specified, however that may not have the downforce, the cars with the downforce may have to make a stop more per race.
Also it would mean that the teams couldnt put ballast at the rear of the gearbox and in the front wing to dial out over or under steer as quickly and as easily. The only way to do this would be via a better mechanichal set up and better aero.
Id also tighten up the ballast rules with the types of material that can be used, as some teams are starting to use even more exotic materials for ballast as a small ballast package will be better for packaging. Personally id restrict ballast to just plain Steel.
The way teams would get arround the ballast regs that way is by having chassis that were slightly heavier at the front and nose boxes and wings would become heavier as they would be outside the wheel centre line at the front. It would become a way for teams not to fail crash tests as well. An extra few layers of carbon would bring the weight up by say half a kilo or so, and flexi wings could more or less be gone as teams want wings to weight a little more as well.
Some teams last year with the mandated distrubution were over weight by as much as 20Kg just so they could get the Pirellis in their sweet spot, and with this get better tyre usage. This would be in effect be outlawed, meaning that some teams may have problems with switching on tyres (Cold graining as a posible result) and some would have a problem with over heating tyres (Blistering as as a posible result) some teams would be in decent shape. It would also be a way for ballancing aero development Vs mechanichal development Vs tyre development as if the teams got a handle on the tyres, Pirelli would become more aggressive.