FYI:
Almost every type of tanking is completely broken
The only ways tanking work are Armor buffer tanking and the Minmatar Logi+Focused Rep tool (the one with 100+ HP/sec) and Gal Sentinel combo. This reduces most incoming damage to a tankable level but still most of the time you win because you have a large enough buffer as your tank breaks when a second guy comes in.
Passive Shield tanking: Does not work because we have a delay (why?)
Active shield/armor tanking: No active mods
Shield buffer tanking: Does not work because of low HP increase (tbh it-¦s not very effective in EVE likewise)
Speed tanking: Barely works on scouts (damage should be reduced with higher speeds)
Signature tanking: Nope because of signature is not involved when calculating damage
Another thing is that the DPSs of all weapons exceed any tanking ability. Let-¦s take your proposed rifle changes:
Even the weapon with the lowest DPS has 361 (RR) which is with a fully skilled Gal Sentinel 306 DPS. Assume every second shot hits he still does 153 DPS. A Minmatar logi can repair up to 126 DPS so your tank is still broken. The only way you survive is because you have a lot of hp and thus survive until he has to reload and you have a HMG with a lot of ammo. So you can kill him before he can kill you.
To get to the topic(finally):
As I propose you won-¦t add active mods or shield transporters in near future the best way to improve shield tanking is by improving passive shield tanking.
Remove the shield recharge delay, shields should repair all the time
Shield recharge rates should be like in EVE, fluent
It should take a certain time to fully repair your shields, if you add extenders it still takes the same time -> better recharge rates
The recharge rates should be better the closer you get to an empty shield
The recharge rates would require a bit of tuning of course
https://wiki.eveonline.com/en/wiki/Passive_Shield_TankingAnd most important: Reduce DPS!
DPS should be at a sustainable level so you really can tank at least one enemy or maybe even two-three in a sentinel
A DPS reduction by 75% for example would be fine. Damage dealing classes like Assaults should get a decent DPS bonus then so they would be able to break a tank quite easy. It would also differentiate them from other classes.