Signpost rhymes with:
sternpost, bundespost, goalpost, guidepost, lamppost, outpost, sternpost, almost, amerihost, anteriormost, bundespost, cohost, foremost, goalpost, guidepost, innermost, lamppost, northernmost, outermost, outpost, overdosed, pancoast, seacoast, southernmost, sternpost, suncoast, uppermost, utmost, westcoast, westernmost
Signpost sounds like:
skimpiest, snapshot, sniffiest