Dangerous exercises

[Hans]

If you have long femurs and short, stiff iliopsoas muscle (many people have this isusse without knowing it) doing squats and deadlifts is injury waiting to happen to your lowerback and knees
Stick to leg press, lunges, stepups and seated leg extension machine, RDL are also fine, and funny enough I discovered that pistols are just fine in this case unlike regular squats (probably because your lowerback is a little curved during pistols)

Squatting properly with long femurs is definitely challenging but in general not impossible:

With long femurs your butt shifts more backwards on the way down, so you are forced to lean more forward to balance out. That's bad. But if you squat with a more open angle between your legs ("spread your legs"), you artificially shorten your femurs (look from the side), and your butt will shift backwards only to a lesser extent. Then you do not have to bent over that much. This requires some flexibility in your adductor muscles though.