I use a 20 gallon concord pot with the basket (ebay) Great pot.1/2 auto siphon fills a 5 gallon bucket in one minute.So I don't use a valve.Do yourself a favor and buy the basket.I forgot to use the basket once and it sucked squeezing a sticky bag.And it makes for an easier sparge with an open bag in a basket..I made this hoist and it works awesome,I brew in my kitchen and a mounting a pulley on the ceiling would have led to a divorce.
https://www.homebrewtalk.com/showthread.php?t=508766
Two thing...don't mount a pulley to the ceiling...mount a plant hook.
Squeezing also is not necessary. If you forget your basket or just choose not to use it, let the bag hang until it is time to chill. In my 9 gallon (net, 10.5 preboil) system I loose two measly cups of wort by not squeezing or about 1.2%.