I can't go any further because my rad suits are only level 2

I have visited the Ag Center, Highpool, the Rail Camp. I have visited a few shrines and even one cache in the radiation.

It seems I can't get to any new places. All I can do is wander around and get attacked by three-man bandit teams or six-lizard gila monster teams.

I have radiation suits. They are low-quality and allow the team to survive level 1 and level 2 radiation clouds.

I could just use the Ranger editor to get high-level radiation suits, but there must be some way to do this without using the Ranger editor.

Am I just supposed to wander around until I discover high-level Radiation suits on the bodies of bandits?

Update: I have some spoiler-heavy insights:

There are two sets of turrets; one big and one small. To attack the big turrets directly is suicidal; the small turrets are weak. The small turrets are located in the "Prison Valley" and they protect "Red" the merchant. They are basically white or silver. They have about 100 hit points. The big turrets are black and huge and mounted on buildings in the actual "Prison" map. They are behind a row of white stones and an intercom. As you approach, Danforth speaks to the party from the intercom. The big black turrets have thousands of hit points. It is not necessary to attack the small white turrets to get to Red, but it is the easiest approach. The other approach is to explore the entire map until you find the back door to Red's hideout. Note that after you talk to Red, you still have to explore the Citadel to locate the quest target.

There is a quest that gives you a +4 radiation suit, to start it go to the prison camp and find Red iirc. then go back to RC and follow quest from there.