The crew limits can be misleading, as the CR90 can certainly take more crew as passengers. If the skeleton crew is 30 for the corvette then it is pretty much the same as for the DP20 (I think it wouldn't need 45 people just to fly it). Basically the corvette is a more versatile design that can accommodate lots of passengers whereas the DP20 is a pure military vessel. Looking at the 3 team types we have I would say that the gunnery team is ironically the least appealing, who wants to spend more energy for an extra hit. The engineering and sensor teams are the ones I would go for. You really only need one each of these at most. Cargo upgrades should be limited as this thing is not built for carrying cargo although Frequency Jammer, Backup Shield Generator and Engine Booster seem appropriate upgrades, even if only one were allowed.
The sensor upgrade and turret upgrades open up all many of extra stuff. Do we want to see a DP20 with two ion cannon turrets? Likewise the missile slot is open to use any type of missile, that seems plausible but specific mention is made of concussion missiles so having a unique DP20 title hardpoint that is a "reusable concussion missile attack" is one way around this.
In a version with only 4 hardpoints (2 per section) I would have in the fore section the primary turret representing a turbolaser battery alongside a unique missile hardpoint and a quad laser hardpoint. The aft section having a quad laser and turbolaser hardpoint. So basically 2 turbolaser and 2 quad laser batteries with a missile attack. If there needs to be a ruling you could have the missile hardpoint be able to fire directly ahead or directly behind if you really want the capacity to launch in either facing and this would be a unique feature of the DP20. That seems like plenty of firepower options to me without going to extremes.