Pulzcul,
In the absence of design/layout/drawing software you can easily estimate/calculate it the old school way that I’ve used many times to visualize placement of furniture, appliances, and seating in a given space in a new home, apartment, office, etc. Works excellently for estimating pool table configuring as well:
Simply get a sheet of paper or cardboard that's more than a foot square.
Pencil-in your room size as a square measuring 12 1/2 inches by 12 1/2 inches which represents your 50 foot room on a scale of 1/4 inch = one foot
Valley 7 footers typically measure 53 by 93 inches on the exterior dimensions -- your prospective ones in whatever brand you may buy will be pretty similar. Get a sheet of some heavyweight paper stock (cover stock or construction paper) and cut out 10 (or more) rectangular pieces measuring 1 15/16 inches by approx. 1 1/8 inches. These will represent accurately-scaled versions of your 7 footers. Then cut a couple toothpicks to just shy of 1 ¼ inches – these will represent a few 58” pool cues, accurately scaled, and will help you judge clearances. Now you're ready to experiment by moving the table simulations into the optimal configurations for your square footage and see what works for you.
Shelves at least 45 inches off the floor can take the place of pub tables for holding drinks and playing accessories if you’re tight for floor space and won’t interfere with a shooter’s backstroking in any way.
You need at least 4 feet of space between adjacent tables, and 5 feet of clearance from walls or other vertical obstructions or equipment.
Remember to pencil-in the scaled version of that 18 by 18 seating area.
I’ve laid out a number of rooms this way in the old days.
Arnaldo