Need help with saddle fit for rider... Prestige Desert Light

The Prestige Desert Light I just bought has fenders with cage stirrups. The fenders have these knee / thigh blocks built in. I can’t tell if I am supposed t shorten my stirrup and push my knee into the block (in which case it’s uncomfortable and I may need to order a long fender). Or am I supposed to lengthen my stirrup and have the block rest at the top of my thigh, which puts me in a very long-stirrup-y position.

My horse is on layup, so I can’t trot around and see if it’s comfortable.

Does ANYONE have a photo of a person actually riding in one of these things, so I can see how the block is supposed to be in relation to the rider’s leg? Google isn’t helping me!

Can’t help you with the prestige specifically, but I have switched my fenders for 2 inch biothane “leathers”. So much comfier than fighting with a fender.