That's the player's fault for taking 7/8+ shots without thinking about ammo rolls. Weapon reloads are common equipment and quite handy.
From reading your reports, IMO you have had 2 of the most difficult games for the defender due to Treacherous Conditions, poor choices and bad luck and this is causing you to believe the scenario is bad.
Pit Slaves will mulch pretty much any gang in any scenario with -2 to hit on shooting.
This is the second game of the campaign yet with a small gang like Pit Slaves you have multiple guys with Sprint skill and multiple guys with 2W? Seems like you had a lot of good luck with that gang so far.6 sustained fire shots even when the targets had already dropped but he did take 3 wounds off 2 of my dual wound minis.
I will reduce the highest level rewards a bit and see how we get on. In the meantime, please give a few test games a go without TCs.
Did you roll off to choose table edge? If you win, make sure you pick a side perpendicular to the bridges. Also if you're playing a Shooting heavy gang, try to force a few open areas with your terrain placement and block off any obvious safe routes.I put down alot of difficulty terrain this match but was countered with simple bridges/pontoons being placed over them.