I like any of those space saver tanks, of which the engine internal tank is possibly the best. Some like the bow tank as they tend to sit close to the engine and need the weight to somewhat balance the boat. Nice fit under the engine, leaves the rest of the boat open.
Yes, I have seen them too, I would have bought one when I bought the dinghy if I was buying the motor too, but since the motor waited a year (I rowed) so did the tank. Now in retrospect I am glad I got a used motor that included the extra tank with a long hose. It is bad enough to have a 60# motor on the transom, to have the gas there too would really make the bow high. I had to buy an engine handle extension so that I could use my body weight to keep the bow down at full throttle. Even with the gas tank at the bow I still dangle my legs over the bow for added bow weight. I will admit the gas tank gets in the way and wish I could use the transom tank but not with a heavy 4 stroke on the back.
I was going to buy one of those tanks for my RIB.
Then I bought a plastic tank at a Rummage Sale for $1.00. I think it's from a riding lawn mower, maybe holds one gallon, with mounting holes.
No drink holders though.