Tossed Salad
by Kegler

Eight related answers are clued via wordplay only.  Each of these answers needs to be treated similarly     
before entry into the grid; the five-word phrase in the shaded diagonals (from NW to SE, then SW to NE)
will lead the solver to how this is accomplished (in two cases the instructions are followed rather loosely).

Across 1 Rafters' locations involve first of pests in invasions 5 Endlessly slide downhill following company drinks at the ski lodge 9 Peter out with Mel and Tom, at first 10 Essentially, formic acid is a mineral 12 A person goes halfway 13 The last of the Greeks, to me, gave offering 14 Foot of bed covered by sheet's flowering tree 15 Racket string from California and Utah with twisting at the ends 17 Ultimately, Pop is embraced by stubborn clan 19 Irritate famous model, then let up 20 The oil splashed stone tool 22 Sage starting with the second type of income 24 Father returns empty pail to house, finally 28 Intonation of absurd article 31 Run after officer, one with dried coconut meat 34 Snoop is sure, reportedly 35 Tow if returning for tank of gas (hyph) 36 Luxurious tapestry from secular Rastafarian 39 Extremely poor one in France 41 Telescope user, pervert, rents a room 42 Tribe turning right to left in intersection 43 Excited by upsets in secondary categories

Down 2 Rhodesia, e.g., isn't providing sponsorship 3 Aircraft window section has second piece of glass 4 Not bright to ultimately waste money 5 Draw tight and start to close in on church 6 Almost arrived with moving machine part 7 No scope 8 Alert watchmen start shift amid disputes 9 Going around Emil 10 Rear of cocoon absorbed by insect in about 30 days 11 Attorney couple from Texas 16 Measure of time is later mentioned inside 18 Tart's price, oddly 21 Obvious start to “OK Corral” 23 From days of yore, one penny includes beginning of inscription 24 Operatic songs by Ms. Callas, removing top and starting to shimmy 25 Run away with park light 26 Miniature assistant nearly flew back 27 Ace enters gym room, initially 29 Navigator ultimately immersed in form of carbon marine life 30 Exams set back twice, the second time without error 32 Wing's adornment, for the most part 33 We're eventually going after unusually pure Indian coin... 37 ...or returning with shard from Indian city 38 Request a second thousand 40 Deprive of one's belongings, Mr. Reiner

Solution