Use a 55W car headlight bulb in series with the positive lead. Bulb will be low resistance when cold, and if there is a fault on power on it will glow brightly, but if it is either cold or very dim ( barely visible red glow in the dark, around 2V across it, then it is fine to bypass the lamp and apply full voltage. Have a 30A fuse (or whatever the transciever uses) in series as well, just in case something lets go.
For transmit you just use a dummy load, as most transceivers typically always apply power to the final stage transistors, just doing the PTT using switching of the drive, though if you have one that does not use 2 55W lamps in parallel, same fuse, and on transmit at low power setting they should be barely lit, with 5A of current flow and cold, they will slowly warm up over a second or so, enough to show the TX stage does not go bang. Then you bypass the lamps, and test at full power.