100BB is not deep for a cash game.
I know but, the exciting thing about this concept, for me, is that as play continues, stacks get deeper and players have to adjust their play in ways they are not used to in tournaments. If you start with >200BBs there is a minimum amount of adjustment to make.
Even although the blinds were .25/.50 the game played more like .50/1
I"m assuming that people opened the betting with larger bets than you would expect at .25/.50? if so, why is that a problem?
You/ They can play how you/ they want. Cash game play is about adjusting to different opponents and taking their money. if their opening is too high try something other than 3betting x3 their bet, surely. or let them grab their .75 winnings, and play the next hand.
I have a further question: Are you able to bring a small extra stack of "tipping chips" t the table in additon to your starting stack?