Tai-otoshi / o ouchi gari

Anyone have any good tips for this combo? I did randori for the second time in 6 months or so (the person is literally 100 pounds heavier and 6 inches shorter than me) and I nailed him once with a tai otoshi. I tried o ouchi gari a few times but he kinda stiff armed me away and then shucked me down to the ground (I was stupid and kept going for it with one foot in the air even when I didn't have proper kazushi or body contact). Since he knew that Tai Otoshi was the only attack I could really get him with he just sat back on his heels and I could not get him. Does anyone have any tips?

I started working on one entry (hard to explain) where I push with my tsurite and pull with my hikite, which turns his body so his front leg is forward (we're both righties) which allows me to get inside, and THEN do the opposite, which puts his weight back on his right leg and then I could do o ouchi. It felt real nice but I didn't have a chance to try it out in randori.

Any others?

"Kouchigari to Taiotoshi - Tori tries Kouchigari but does not put his weight on his attacking right foot, Instead he forces uke into stepping back by pushing uke with his body. As/when uke steps back, tori applies Taiotoshi."

Taio to kouchi leg grab or kouchi makikomi.