Drop this into a .bat somewhere and you can then drag+drop one ore more images onto it to create a multi-page PDF document.

to-pdf.bat

@echo off
if %1.==. goto No1

bash -xc "a=(); for i in $(seq $#);do a+=(\"$(wslpath \"${!i}\")\"); done; convert \"${a[@]}\" -auto-orient \"output$(suffix() { local v=$(cat); if ! [ $v -eq 0 ]; then printf ' (%%s)' $v ; fi ; } ; find . -name 'output*.pdf' "|" grep -E '^\./output( \([0-9]+\))?\.pdf$' "|" wc -l "|" suffix ).pdf\"" -- %*

goto End

:No1
echo No documents dropped onto script; terminating.
pause

:End

Requires ImageMagick's convert utility.

If you're getting security errors from convert, run this once:

sudo sed -i_bak 's/rights="none" pattern="PDF"/rights="read | write" pattern="PDF"/' /etc/ImageMagick-6/policy.xml