I'd propose:

Marksman Scrambler Rifle

Longer range Scrambler Variant (somewhere in the 90-110 range). Slightly higher damage than the standard. Can only fire charged shots. Without a heat reducing passive, overheats within four chained shots. Slightly inflates the shield/armor damage ratio, increasing damage to shields and reducing damage done to armor.

The Breach Scrambler Rifle would already fill this role.

Instead of adding newer weapon variations, why not fix the currently existing ones first? ie heat reduction? Also make standard scrambler range > or = TAR and assault scrambler range = AR

Makes sense

... doesn't the word Breach indicate that it's meant for close-quarters combat?

Instead of adding newer weapon variations, why not fix the currently existing ones first?

Assault Scrambler Rifle
Currently, the Assault Scrambler Rifle is little more than a normal Assault Rifle with altered statistics and taped-on heat build-up. I suggest a change. Instead of being a general, boring weapon, the Assault Scrambler Rifle has increased damage the higher the weapon heat. Like to live dangerously? Try to keep weapon well heated without overheating the weapon.

TL;DR: Just as with Laser Rifles, Assault Scrambler Rifles reward sustained fire, but to a lesser extent.

Assault Scrambler Rifle
Currently, the Assault Scrambler Rifle is little more than a normal Assault Rifle with altered statistics and taped-on heat build-up. I suggest a change. Instead of being a general, boring weapon, the Assault Scrambler Rifle has increased damage the higher the weapon heat. Like to live dangerously? Try to keep weapon well heated without overheating the weapon.

TL;DR: Just as with Laser Rifles, Assault Scrambler Rifles reward sustained fire, but to a lesser extent.

Burst Scrambler Rifle
Similar to the current Scrambler Rifle, but with burst fire capability. Tap R1 to fire a volley of uncharged shots, emulating an Assault Scrambler Rifle, or hold R1 to charge a single, powerful shot, emulating a standard Scrambler Rifle. Unfortunately, this added capability requires sacrifices be made. As such, shots take longer to charge and burst fire has less range than normal.

TL;DR: Gives up some specialization for increased versatility.

Breach Scrambler Rifle
Also similar to the current Scrambler Rifle, but focused mostly on using charged shots. The Breach Scrambler Rifle has a smaller clip size, longer charge time and uncharged shots produce more heat, limiting standard usage. For some, these consequences may be worth it, as the Breach variant has greatly increased charged shot damage and range.

TL;DR: Reduced effectiveness in close quarters combat, but greatly improved charged shots.

I think the current variants are more than sufficient given we still have two more Light rifles yet to be released.