Pre-Sales Engineering Question: Bridging/Switching Capabilities Multi-Chassis HA Cluster

[BSeklecki_GE]

Assumptions: Active/Active (or Active/Standby) HA
Assumptions: VDOM-Mode
Assumptions: Routed Mode

If running an active/active (or active-standby) HA mode, dual-chassis (something like the 100F), and implementing Bridge Domains and VLANs on the soft or hardware switch module, is it possible to configure a Dot1Q Trunk be passed directly between the two chassis?

(Effectively creating a chassis-spanning software (or Hardware) switch, that obviates the need for an an external switch)?

If so/yes, what are the limitations ?
* I know that FortiOS software switches run STP, I've seen all the GNU/Linux kernel brctl(8) stuff hiding in the background
* Could one run LACP between the chassis?
* Ideally, could one ( optionally ) also trunk these VLANs to an external switch as-well (with our without LACP)?

This question comes from a requirement where:
* Project requirement where space/power are at a premium, and IRB/CRB on a single chassis would be ideal.
* The switchport density requirements are extremely low

Cheers, ~Brian

[BSeklecki_GE]

NOTE: In the Cisco world, one would simply install an independently-managed Catalyst EtherSwitch module into a NM/SM-X module port on the device (like an ASR4K); providing one with MACSEC, 802.1X, UPOE, PTP/1588; one can even Stack the EtherSwitch modules.

Hypothetically, if the ASR4K is the base chassis/platform, I suppose the FortiVM could be a guest on a UCS-E server blade module in the SM-X module as-well.

Thanks-in-advance for candid replies ~Brian