I would make a few suggestions for these directions.
First you can buy the tube already coiled from Harbor Freight for $1.99 but it still comes in 25 feet sections so you still have to connect 3 together after cutting off the metal connectors. Getting it IN the big pipe is much easier becuase it's already coiled.
Also if you try hard you can find flat caps or spigots for the ends of the big pipe without the bow that the cap shown has. A bonus is you dont have to use the knockout version for the bottom. But the biggest advantage of this is because then you can use a small bulkhead for the tube passthrough with two reducer tube connectors instead of relying on glue. Polyethelene is highly resistent to glue. In fact most consumer grade glues are shipped in polyethylene bottles. God bless you if you can get your hands on indutrial 3M polyethelene glue, if so send me a tube.
I reccommend throwing a healthy amount of 5 min epoxy on the connections as well because you won't be able to peek in later to make sure it's still connected.
Also, make sure you use a pvc cleaner and coat the pvc connections really well with pvc glue.