Yea, don't replace Ditto with Dolphin Editor... Dolphin is not a clipboard manager...
I'm not a developer, but I'm guessing the MLO will detect any Windows font that you have installed. So if you have an all-cap font, then maybe. As you mentioned though, they are probably clunky-looking. An all-cap font won't be crisp looking LIKE THIS TEXT HERE.

Which is "It will look like this." in Ballonist SF font.
Side note though: If you're a clipboard manager user... It's been a while since I used Ditto. I'm pretty sure ArsClip will paste all caps. For a long time I have been using Clipboard Help+Spell. It has some nice customization formatting presets (that's part of the reason that I didn't need Dolphin installed). See image:

CH+S is "donationware" so you'll get nagged to donate a couple times. It's a decent app. Worth a donation. Or eventually, you CAN get it free.
Similar to Dwight's warning in another thread though: Don't burn all your time trying to find the perfect tool.. ;-)