>>4416159Seconded
I 100% get the dream is to like, grab her leg, but you really want something good to get leverage off of.
Also work on your core, do some pilates or something. Doing those good, deep thrusts is tiring, and you need to get some resilience to keep at it.
I get wanting to be a purist, but I reccomend looking into a stimulation gel or cream, too. Find something that works for both of you.