Virgil;
pvc w/use is a thought. maybe you could lay the pvc down , 2/3 buried so as to keep it visible yet not a trip hazard. Then you could run the pvc unglued, so as to reclaim it afterwards. Are there sub-panels? A run of #6 triplex with a 4th #6 wrapped around it fed via 50A GFI breaker may be cheaper...
you won't get quadriplex on short notice
beware, a 'tent' has been argued as a structure ( 250-32)
if this is a yearly event that you could make good on, rent annually what is not permanent and U may make back much mored $$$$ than U have put out in the first place.
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