will heat be an issue?

No you should be good if you mean the normal heat that comes off of those.

I think the place youd most likely notice a tempurature difference is at the heat sinks on the back of the radio, or on the side.  The radio will still be warm because air doesnt circulate in the cavity where the radio sits.  Even if your head unit only generates a small amount of heat it will sit there and accumulate because it doesnt really have anywhere to go.  If you really want to know what kind of temp difference turning the amp of does try using a dmm with temp probes.  See if you can install the probes in the radio cavity with the radio and run the wires safely through the dash to your meter.  Turn your radio on and use it for however long you normally do. ( dont forget to hook some speakers up so the amp has to work to drive them.)  Then try it again with the amp turned off and see what the temp difference is.  Last step would be to put the eq in and the radio (with amp off) and see what the temp is.  If its less than or equal to what it was with the amp on then you should have no problems whatsoever.  I know there are alot of other circuits in the radio that generate heat  but I think it would be safe to run the radio with the amp off and the eq in there with it.