I've been playing with Munich semi-frequently in my recipes (including pale ales / IPAs), and find it takes a deft touch...to echo what Denny said, I wouldn't consider it a complete substitute for crystal malts. If you use too much, the heavy bready/malty notes can clash pretty harshly with some hops on my palate, especially the tropical varieties. I keep Munich <10% in the IPAs I've brewed...as an example recipe that used Munich and turned out well, here's my Wildfire IPA recipe that I brewed earlier this year, based on a recipe by Chris Colby: https://andybrews.com/2020/03/28/wildfire-ipa/
-- this recipe relied heavily on the "old-school" classic American-type hops, and used dark Munich (11 SRM). Note it alsol used a bit of crystal 30.
All that said, I really like Vienna as a base for IPAs, and often just use that at 100% (especially in session beers). I'll often use a combo of crystal 40+crystal 60 to round out the malt profile, but always keep that well south of 10% total malt bill.
So I suppose to fully answer your question, and patterning it after the Wildfire IPA recipe, I might start with Munich I at ~8% of the malt bill, a bit of lighter crystal malt, and possibly fill it out with Vienna as the rest of the base malt, and mash a bit higher than you normally would to fill out the body. It won't be the same beer as you normally make, but I would bet it would be tasty.