Better Settlers by Thom293 addresses this issue by adding over 240 settler variants to the game.
Without Mods, combat armor is not available but Metal Armor will be so, make sure you buy and hang onto this armor for you and your Guards. While in the Workshop menu, walk over to Settlers and select them, then select food to put them to work.
Familiarize yourself with the ins and outs of Settlements and Crafting. Report problems with download to make sure to take the Fusion Core with you-else settlers or attackers might get in the suit and use up your fuel.
