I’ve wondered about the vac hose often- bought one from LeeValley in CA and hang the expense! I have thought about using pool vac hose though,
On another note, I designed a block out piece for the bottom of the Makita which seems to work well redirecting the exhaust on the LR2 it’s in this post makita infill. If you are interested in trying it I’ll upload the STL - I haven’t tested it on the LR3 so haven’t published it.