Sounds more like you need 1.4x or 100-400 or a big prime. If you have to crop so much as you end up with that issue more pixels do not necessarily help.
2000 740i-Annalisa and 2008 335i-Weebl. Weebl may wobble but has DTC
2012 X5d in Sparkling Bronze ( The Ultimate Cat Carrying Machine):2017 A3