I'm looking to buy a marquee for a wedding for 100 guests. I have seen a few online that I'm interested in, but I'm not sure how the floor works. The area we're looking at is relatively flat, it's a gravel surface. There is a slight slope, does this need to be levelled out by the marquee floor? The marquees I'm looking at are 500gsm PVC material, does anyone know anything about that, whether this is what I should be looking for? Any hints or tips appreciated, thanks.