Your basic premise is that larger hulls should not be able to profit from sites designed for smaller hulls. I agree with you particularly because there is zero risk involved. But it’s not just about hull size. T3 destroyers are just as overpowered. So are T2 frigates. It can be argued, as you yourself have, that some of the lower end stuff is too easy even for T1 frigates or a properly fit corvette. Although I understand the rational behind the idea, your execution is ham-handed and just plain sloppy.
I think the real issue is improving enemy AI, which currently does not exist. If a battleship warps into a site full of NPC corvettes and low end frigates not equip to handle a battleship, the NPC ships should warp away if they are taking damage or being destroyed without returning adequate damage. If a ship is 100km off and able to snipe targets those enemy targets should warp off grid instead of running headfirst to their deaths. If this happens then the site would enter into a 1 minute timeout period after the player leaves before the pirates return. If the offending ship remains long enough or starts attacking structures, comparable enemy ships should arrive on grid that are capable of actual engaging the player in a meaningful way. Similar to the mining fleet response forces, but without being overpowered. They would be comparable to lowsec content. These fleets would be tailored to the perceived threat and only attack the instigator. So a battleship would get battleship equivalent pirate fleet, a cruiser would get cruiser sized ships, etc. And by arrive on grid I mean right on top of them or within range to effectively return fire. This game has the AI code to do this. The diamond fleets and the Triglavians have advanced AI. I do not understand why a similar AI sophistication cannot apply to ALL NPCs across the board and not just the overpowered types. I’m not even talking about really advanced AI. Just enough to know when they are utterly outmatched and at a complete disadvantage.
I would also like to note that there is an adherent disconnect when it comes to these sites. That being that the escalations these players are looking for are generally of a higher level than the anomalies they are derived from. It’s my understanding that doing sites of the correct hull size would render escalations for the next hull size up. The escalations a frigate sized site provides are cruiser level. Simply barring medium to large hull sizes would effectively make it near impossible to play with one ship if your goal is doing escalations. It’s a problem with the basic mechanics of anomaly based escalations in particular. Someone please correct me if I’m wrong.
For this reason I offer a second additional recommendation to the improvement of the AI. Make the escalations match the content they are derived from. T1 small sized hulls should get escalations they can complete with a small hull. And place the ship size limit on the escalation site’s acceleration gate. If the escalation is for T1 frigates then only ships up to T1 frigates can enter. If it’s rated for T2/T3 small hulls and Cruisers then only ships up to that level can enter. If rated for T3 medium hulls and battleships… you get the picture. And in regard to the response fleets that spawn, those people in the larger hulls should still get escalations that fit their hull size from dealing with the response fleet. But perhaps with a lesser chance of receiving an escalation? Enough to make it where doing the proper content is more efficient than expending more time waiting on the response fleet + having a much lowered RNG.