You're going to be using a garden hose fitting some where. Most likely outside the waste tank. You can get a male garden hose fitting to male pipe thread in 1/2 or 3/4. If your pump pumps high volume I would use 3/4 in all the plumbing if not then 1/2 should work fine for all the plumbing. Easier to keep everything one size imo.
They are made to fit standard pipe sizes, pvc etc. They fit really tight and will need a hole drilled to the size they recommend for what size uniseal your using. They give you the exact drill bit size.
Once you force whatever pipe your using through, which takes some strength and dish soap to lubricate it seals super tight.
I have been thinking about running a 2+ft hose from the inner bulkhead to the intake filter and looping it up and fastening it to the upper part of one of the stacks with the filter pointed down so I can open the lid and pull the filter out to clear it if needed even when full.
I see no advantage to leaving the filter fixed near the bottom of the tank, especially when it is so vital to keep it unrestricted.
So I guess a flaccid hose is no big deal, like my wife always said.