In this particular mod it is worth it to set up one class with an smg of your choice, lightweight, s&g, 3X semtex and a smoke. Also the RC. If they are all spawn trapping you then it is often possible between the nades and your gun to get 3 kills. Find a place for some cover and spam them. Then use the RC to defrost three or four guys. I see that happen all the time and a team that only has one player left comes back and wins. Every one you get has to be defrosted first, requiring attention from his teammates especially if they have to move to do it, and when finished he starts back at his own spawn.
Others have asked for what you propose and I have politely said no. Otherwise spawn protection is used as a means to sneak up on opponents or stand in the open. Then to get a shot off the moment spawn protection runs out before he even knows you are there to defend himself. So I added s&g and the RC defrost ability. Spawn protection, as the name implies, is supposed to be totally defensive and allow you to leave the area to find cover. When it runs out if you are out in the open still you would likely be running anyways and your weapon lowered.