Back in the day (1980s) we used to play 20 over mid week league cricket - evening games. The boundaries were the same as for weekend games, the only variance being where on the square the strip was cut.
It was a different mindset back then. If you scored 120, a run a ball, you expected to be able to defend it! 150 and you were on easy street. Obviously we weren't pro standard, but we tended to be much of a muchness on ability so games were usually quite close.
As an example I recall one game where the strip was cut on the edge of the square so there was a shorter boundary, but it still took a very good hit to clear it. We scored 170-odd with one of our openers getting a ton. The opposition knocked them off, one of their opener's replying with a ton of his own. The relatively shorter boundary obviously playing a part. This was on a first class grade pitch/ground which hosted county and A list matches.
There were no restrictions on bouncers or fielding, or on bat size.
Heavier bats were coming into vogue, this was the era of the Magnum and Jumbo and the Symonds Super Tusker, all of which were in common use on the club scene with bats in the 2-12 to 3lb range very much in favour. Using them effectively was a different matter - today's first class players are obviously fitter and stronger on average than the first class players back then - I wouldn't like to hazard a guess on the club player comparisons.
I think restrictions on bats would be a bad move. I'd be in favour of bigger boundaries and less draconian no ball rules.