This is what I use. I have a 12ft fiberglass canoe and I load it with this pretty easily. I am not that tall of a guy either and don't think a normal rack would work when I go out by myself. https://smile.amazon.com/dp/B0024FOTOW/ref=cm_sw_r_apan_glt_fabc_PE8S9MAXCDHMSMX2PKB7
I have a Mazda 3 as well! it is a different generation than yours though. i just remembered the key to what makes my system work. I have a hitch on the back for a bike rack. so I would also use a canoe loader bar like this one. It worked for me because i already had the canoe loader bar thing from using it with a previous truck, and the hitch was there for the bike rack. so that wasn't an up front cost to me. but really, i suggest it. the hitch is useful to have and easy to install yourself. and this bar is cheap. Look at the pictures of cars using it on the amazon link.
This reminds me a little bit of a thing I got for loading my kayak. I keep it assembled, but it is two pieces held together by a cotter pin. Depending on how far this would stick out when driving, you might be able to do something similar so you can separate it into two pieces you can put in the back of your jeep. Just a thought.
This is what I have. I bought it because I was about to buy a 16 ft kayak, but I never did.
For my Discovery I use one of these and like it: Reese Towpower ~70$
I cannot recommend this enough, I know it cost money and not everyone has a hitch receiver:
https://www.amazon.com/Reese-Towpower-7018100-Canoe-Loader/dp/B0024FOTOW