Based on my experience (others may vary), Drain Torpedo is uneccessary on most Plasma Ram loadouts because Plasma Ram completely ignores/bypasses shields (but not armor modules); it is usually more useful to have Disruptor Missile as your secondary module so that you can also ram ships that have armor modules. You may also want to consider using Thrust Amplifier as your Internal Module; personally, I find Plasma Ram + Warp Jump discombobulating to use (extremely difficult to correctly line up Warp Jump with the necessary accuracy to have the exact Warp Jump-exit point and ship orientation desired), whereas Thrust Amplifier allows a smoother, easier-to-aim attack approach.
The Dola is the hardest ship with which to use Plasma Ram due to its sluggishness, even with Warp Jump. Though hypothetically it could be a powerful ship to use Plasma Ram on due to its greater HP and close-range weapon damage, the extreme difficulty of predicting exact Warp Jump-exit point and the Dola's sluggishness enables more agile ships to rather easily dodge/avoid ramming attacks; the Dola still does not have enough HP to easily attack even more sluggish dreadnoughts.
Ontranto should be easier to use Plasma Ram on, though still not a cakewalk (even using Plasma Ram on the Vindicta takes time, effort, and practice to use skilfully). You will need to be sneaky, use cover, and carefully select (vulnerable) targets that you can reach without getting yourself killed.
Be sure to use Flak secondaries on your ram ships, as you will be within range to use them during your ram attack.
Also, eventually obtaining Officer Briefings (ex. Module Amper, Engine Rigger) that are stuck behind the T4 wall will make using Plasma Ram a bit easier.