Here's what rhymes with sumptueux.
no so know go though low show co blow pro row tho fo foe ho lo bo doe dough mo po ro toe wo woe tow yo beau bio ceux faut goe hoe jo ko sew soe vo beaux cho dau mow noe roe sho tuo yeux zo bro rho trow whoa doh below ago flow grow slow snow throw glow quo undergo audio fro crow patio thro nouveau tableau uno dicho floe tableaux topos dunno stow throe trousseau sloe tarot turbot undertow kayo matzoh pekoe trousseaux borzoi schmo schmoe although radio embryo plateau studio bestow chateau hello indigo polio propos vertigo aglow medico outgrow rodeo spatio chateaux plateaux chapeau kapok oleo deathblow bandeau gateau pompano chapeaux fatso gateaux resew ratio buffalo folio portico stereo bungalow dynamo forego forgo aliquot apropos cameo domino escrow siglo afterglow adagio piccolo foreknow regrow romeo tallyho overthrow overflow calico politico mistletoe presidio pistachio overgrow mustachio microdot moustachio portfolio oregano pianissimo archipelago impresario braggadocio generalissimo