What flag would I use so the Bradley in Convoy reforged stops destroying my roadside base?

hi, you can create rules with an entity group, or block it in the convoy config.

convoy config file - set each of these to 0:
Damage multiplier from Bradley to buildings

alternatively,
truepve rules:

"bradley cannot hurt anything",
"bradley can hurt players",

    {
      "name": "bradley",
      "members": "BradleyAPC, maincannonshell",
      "exclusions": ""
    },​

realistically ANY plugin should hook into TruePVE and make that damage optional which is what Convoy does. 

link to default config with these changes:

https://justpaste.it/fhzpm

Thank you. I got confused with the damage multiplier portion in the config - Because it says (-1 - Do not change) and it's already set to -1. So if I change this to 0 - I don't need to add the truePVE stuff? or better to add them all just to be sure?

you can if you have issues. I don't use any plugins which increase bradley damage to buildings. that damage is barely anything in vanilla