I’m tall, too, and yes, sometimes I do have to do a sort of “squat” for a shorter priest or EMHC. I approach with my hands folded low at my waist and open my mouth very wide, with my tongue extended past my lips. (Practice this in the mirror at home, so you know what it feels like.)
Bending over has the disadvantage of tipping your mouth forward, so there is more of a chance of the blessed sacrament falling out of your mouth or not being inserted properly b/c of the angle.
I’m sure others will come along with different opinions, but I think you can feel free to make the sign of the cross at any time.
