1. If you are good at tanking level 4's, sit still at one point and allow the mission ships to gather arround you thus creating a close group of wrecks.

2. If you are into manufacturing including making your own rigs etc then salvaging level 4's is well worth the effort for some of the larger missions like "Blockade", "Mordus Headhunters" and "Angels Extravaganza". A dedicater salvaging Hurricane with T2 salvagers, Salvage rigs and cargos extenders in lows can clear most sites quickly and in one go.

3. An Orca salvager is another option if your wrecks are spread about as the tractor range bonus enables you to get most of the wrecks to you however the lack of high slots means ony two tractors and 1 salvager.

I've found that, if you are reasonably skilled with your mission ship, many missions aren't worth salvaging.

Sansha, Angel and to some extent Blood Raiders are the only missions I really bother to salvage and even then mostly just the battleship wrecks and the odd battlecruiser that I hapen to pass near.

Drones are usually worth looting, as they don't have bounties. You'll need a good sized cargo hold though (pulling a can around behind a destroyer and then picking it up with an industrial works, if less than optimal).

Depends how fast you can clear missions.

If you fit a frigate for salvaging, you can quickly rush back and clean up the battleship wrecks and be done in a few minutes.

Salvage destroyers tend to be used for cleaning up the whole mission, but depending on how fast you can blitz missions, they may not be worth it.

I suggest you try with a salvage-fit Rifter or something, and see whether it's worth it for you.

If not, ask in local (or contact someone from Suddenly Ninjas, ha!) for a salvager to clean up for a share of the salvage.