Fleshlights/male masturbators

I've tried buying two of these. Both times I couldn't get anywhere near close to being able to use them. No chance of them fitting. The first one I had go cut the material open to use it in a very clumsy way (and ended up throwing it away).

The second one...well...the hole is so tight it's not even worth trying.

I'm not huge compared to the standards here. I'm around 7.25 inches long and 5.75 inches girth at the thickest point.

Has anyone had any success with these 'toys'?

The reason I want to get them is not just for pleasure but to be able to masturbate in a way which more closely mimics sex...avoiding death grip and any performance issues that can come with that. I'd like to be able to train myself so that even in times when I'm single I still feel practiced in having sex when the opportunity arises. If that makes any sense.

Edit...I need to buy from amazon (its a privacy thing because they deliver to amazon collect lockers)...if anyone is able to link to some on amazon.co.uk that would fit that would be great.