You'll need to calibrate to get equal levels from all channels no matter what you do - that's a given when adding, changing, or moving speakers around in a surround setup.

In a case where the speakers are really close to the listener, setting the delay for a greater distance just reduces the delay applied to the signal by a few milliseconds. More distance means the sound has farther to travel to reach the listening position. Because of this, the receiver takes all of the given distances, applies no delay to the farthest speaker, and then applies roughly 1ms of delay per foot for the difference in distance between that farthest speaker and all the other speakers. The result is that a note played through all seven speakers leaves each speaker at different times so that they all arrive at the listening position more or less simultaneously. All that might result from increasing the delay is calling more attention to the rear surrounds because the signals arrive just a little ahead of related sounds from side surrounds - degrading attempts to achieve a fluid pan across the surround sound field. Think of a ball rolling from left surround to right surround - if the sound of that ball jumps to the rear surrounds before it has finished in the left and then goes silent in the rear surrounds before being picked up by the right surround, it's not going to sound right. How noticeable this will be is debatable, of course, as most people can't detect small changes in delay setting.

If you have some spare speakers and want to experiment, it's an easy enough thing to try out. I would not recommend entering inaccurate distances for the speakers, and I would recommend getting the SPL meter back out and recalibrating all of the channels before doing any listening tests. I'd also probably try two orientations for the speakers: upright and firing toward the couch, and on their backs firing toward the ceiling. When changing the orientation, you may want to double-check the channel calibration levels.