Hello James.
The crossovers are great for what you want to do.
I have owned the following 3 crossovers, and loved them all - notes follow:
Liquid Logic XP-10 (previously endorsed by Tom Douglas)
Liquid Logic Stinger
Jackson Karma RG
There are a couple of other crossovers, but I have don't have any experience with them.
Dagger Katana
Dagger Green Boat
Pyranha Fusion
XP-10: good rocker, great in whitewater, tracks well with skeg down - a little barge-like if you try to push it too fast
Stinger: Probably the fastest of the crossovers, but no rear bulkhead - interior is 100% open to water - great on expeditions
Karma: Love it. Has rear bulkhead and is well outfitted - front foam splits up the bow storage and foot braces are somewhat awkward to remove for loading, and rear hatch is small, but a great and sturdy boat
I have seen the XP-10 on craigslist a couple of times.
I have only seen the Stinger advertised used when I sold mine.
I have only seen the Karma advertised used when I bought mine.
You may have to be patient to find one of these used.
Happy hunting,
Kent