Trailer Sets 001 & 002 - Although it's an Armored Core model shown on the trailer, I'm sure it can be used for your Gunplas as well.
But then again, I don't really find such trailer sets to be useful. ^^; Apart from taking up a lot of space, your models can perform even less action poses with them. They either lay down or stand up straight, unless you're planning a diorama of course. Using the trailer to hold the extra weapons while your Gunpla stands next to the trailer should look cool, if you're willing to pay so much for something to hold your weapons ^^;
Type 001 (left) and 002, 2,000 Yen each. Available in June.
Images from Toysdaily.
Also coming in June are three optional weapons sets for your models:
Double Blade/Lance
Shield
Naginata/Sniper Rifle
Each of the three sets is priced at 400 Yen each. Not too sure about the scale of these three sets, but judging from its series, they should be in 1/144 scale. Also, in my opinion, even though they are meant to be universal, their rigid shapes don't really look suitable for Zeon mecha which are mostly roundish. ^^;
The sniper rifle looks awesome though ^^
Images of the weapon sets are from Hobby Search.