SP dropping as you've described is not on its own scummy. It's scummy when the Sp dropping is done in a scummy way (like one or two overpowered mechs in an otherwise weak hangar) to try and be matched against weaker opponents (aka tanking). I use a balanced non-legendary hangar for that objective.

But I do agree that I would prefer not to create such a hangar for this. Maybe the real problem is that the objective exists in the first place, not the things people have to do to meet the objective. If the objective stops being a hard requirement then that also solves the problem.

I agree to tar, if you have low hangar and it's balanced there is nothing wrong with it, given that you still have any low star mechs left all, you might not have.. thats unlikely but possible.. I assume even with 7 star mechs, its only making total of 800*5=4000 then you add mortars.. hopefully still low stars... I assume in worst case scenario it's 8000 power.. at that power mortars still can do good kills.. if you use "Fuse Mortar" not Rocket Mortar... Rocket Mortars are quite useless even on 3000 hangars.. The balanced hangar means you dont put low star mechs in combination with one super advanced mech that does all the killings while other mechs never play. If you put normal mechs and normal weapons.. you don't SP drop in my opinion.. I put shotguns, longarms on my Slingshots and Stalkers and I go against Geminis, Savants and stupid mechs like Vortex. I don't see how it's making it unfair to them or being scummy. I must admit I also have Orion and Dreadnought now, but it's only because I'm completeing the tasks on these mechs, I have no choice but to have them until I collect 250 acoins from them. 

I aslo agree to Salt Sponge, I can see mortars an issue for high power hangars, because Mortars are a pain for me even on 3000-4000 hangar power level, I had to buy all fuse mortars to get through the task quicker.. I don't like Mortars.. And for that reason I also dont like the idea of any legendary mortars, because looks like some people just love them.. and if 5 enemies get all legendary mortars and find way to abuse them you probably wont even be able to spawn, you would die straight away.. so I'm highly against legendary mortars.

Unless, like Salt Sponge suggested it's not quite a Mortar.. if you control it it's more like a guided weapon, but can still be a mortar type.. As example cryo/nade launchers are barrage but so is Pod Gun.. and pod gun is barrage type but a completely different weapon in all aspects.. so developers are known in breaking types and putting different weapon into seemingly wrong category.. and so that should not be an issue to create a Guided weapon under mortar category to give us/you help achieving goals without sp dropping.

On this subject I have to say, Half-Life (multiplayer, talking about 2000s) had a sort of guided bazooka with lazer, it was the coolest weapon, it was fun.. But i'm afraid it will not be fun in mech arena.. the weapons here are quite fast, the lag is quite strong... it might still work, but i dont see it being as fun as in Halflife.. There are more chances that developers will screw it up and we will all regret asking for it.. There could be tons of space for mortars, some sort of napalm strikes like in Worms.. giving you poison/burning effects.. it's difficult to say what of this is not going to ruin the playing experience once 5 enemies have it..