Suspension travel vs shock length

[DC43]

Hey guys I'm in the process of building a custom trinagulated 4 link for my 65 big back window shortbed fleetside that will be laying frame. I'm running a bag on bar setup. Will be running a PB extreme up front. My question is for all the guys laying frame how are you guys limiting suspension droop? Are you using the shock to limit travel? With the bag on bar I'm getting a lot more lift than I'm actually going to need and I don't want to run a ridicously long shock if don't have to. But at the same time I don't want to be ruining shocks by topping them out. Being my first build Any advice you guys have would be greatly appreciated. Thanks. Since I know I like pics here's a couple for ya.