2004 Bambi International with two 24 size battery spots on tounge. Want mount 29dc

So I have two battery spots which is nice not complaining. I want to add one big Walmart Maxx dc29. I started the job and added two 2x6, redrilled holes bigger to attach 1/4 inch. I put wood on and secured with stainless bolts and silicone underneath. Looks like it will work for attaching new big battery box now. Painted it all black took care of little rust on battery support. Do you think drilling the 2x6 in four more spots and adding 1/4 inch bolts will be ok? Worried about wood failing and or box falling off. May just return battery and get dc24 but boo lol.