Absolutely the best solution is the one I have in place (slightly superfluous tap on my own back here…):
Use the 50 mm diameter hose. In the shortest length feasible between Kapex and Extractor (measure with some hose you have lying around). It is sold under the product designation D50 MW-AS in any length, so Special Order.
Add two connectors D50 DAG-AA. Install these onto both ends of the hose.
Use the Adapter D50/D36 to connect to Kapex.
Not exactly cheap, but the most suction for your bucks, so to speak.
(For the imperial stalwarts: 50 millimetres is just a hair short of two inches.)
Correction: Noticed in post before this that hose to measure is NAINA in the USA. But since the 50 mm is kind of an industry wide size, it should not be hard to find some in the CUSA.