Kup
+1y
You can actually use the HOK epoxy primer as your sandable primer, just so you know. Generally you can also leave just the epoxy primer on there because they are one of the only primers that do actually seal what is underneath them. So you shouldn't get any rust or anything underneath it. My truck has been in all epoxy primer for like 2 years now and I haven't had any problems.
HOK recommends that you use only their products. You are much more likely to have failures if you mix HOK with other brands. If you want your paint job to last the longest, it is usually best to stick with all one brand. HOK is a very good brand and if you use their stuff from bottom to top you will get a paint job that should last you a long long time.