I guess this is one time I can claim some first hand experience of a topic on this board, and I can tell SV that within 10 feet of a rocket engine, at full chat, is not somewhere any sane person would want to be.
Back in the late fifties I was a frequent visitor the SBAC Farnborough Air Show in the UK and at that time all the latest technology was on show including the use of rocket engines in aircraft. On several occasions the rocket engines were ignited at what seemed head height within about quarter to half a mile of the crowd. This was done I suppose, as a 'crowd pleaser' and one particular aircraft, the Saunders-Roe SR53 would be stood on end and disappear vertically on a long plume of flame with a diamond patterned shock wave in the exhaust flame.
These were engines producing about 4 to 8 thousand pounds thrust and the noise and vibration was incredible.The shock waves could be felt beating against your chest and most of the crowd were reduced to holding their heads in defence. I know that it sure impressed the hell out of me but I wouldn't have wanted to be any closer, even with ear plugs.

One of my lifetime regrets was that I never got to see a S-V lift off, but a shuttle launch was a good substitute. At 3 miles away on KSC's causeway, that was close enough too.
DK