Yes to the first suggestion. It is really too advantageous strategy that has no counter. And I say that as someone who is abusing this.
No jetcanning is not so good suggestion though. Often I am stealing some cargo and I accidentally take some crap items and I want to drop them and cherrypick something else from the cargo. To me that is too restrictive and makes no sense as it applies even if there are no witnesses - like “stealing” at abadoned combat site, or getting away with the loot and be on a safespot, or just getting suspect thanks to shooting ppls in lowsec. There are legit reasons to jetcan, perhaps trading ammo/batteries or just throwing away junk to have some space left.
However, what about a new 1 minute timer that prevents dropping cargo after taking loot from yellow wreck or cargo? That should work. It actually solves fleet hangar too.
That being said, if this fleet hangar abuse gets fixed, the other ones like swapping ships when being attacked (or at least scrammed) should too.
Your suggestion just removes cargo/ship scanning from game. If it invokes suspect flag, then nobody can scan anymore as he won’t be able to stay in space 15 minutes. It also completely removes tornado ganking at tradehubs. It is riddiculous suggestion.
If it gives limited engagement timer, then that is bit more acceptable, but it still does remove tornado ganking at tradehubs as it is super easy for antigankers to get themselves scanned and then dock and undock in combat ship and prevent the ganker to play for 5 minutes at minimum. It also reveals the act of scanning to the target, so nobody (who has enough stuff in cargo to be worth the gank) except those cheaters who uses travel bot will continue ahead with their loot. They either dock and continue later or they dock and unload cargo to bait gankers into pointless gank.
Scanning is already visible if you watch carefully even if the scanning ship uses passive targeting module. If you want to stop them, then go and gank them. That is the counterplay available.